A family of Canadian volunteers dedicated to alleviating poverty in Africa. A group of intrepid German retirees on a tour of Turkey and the Middle East. An Iraqi who had gone to Baghdad seeking refuge from the jihadi violence of his hometown. A Canadian audiologist who had fallen in love with Indonesia.

They were among the scores of people slaughtered by Islamic extremists in four countries last week in spasms of bloodshed that left loved ones stunned at the randomness of the killings.

“It will never be understood: ‘Why you?’ No one can give an answer,” observed a relative of one victim, Karin Franke-Dutz, 70, a retired teacher who was among the Germans killed by a suicide bomber in Istanbul. The relative, André Franke, summed up a universal anguish in a Facebook post, saying, “Incomprehensible that we lost such a cordial, wonderful person in such a terrible way.”

The settings for the attacks were the softest of soft targets: a shopping mall in Iraq; a hotel and a cafe in Ouagadougou, the capital of Burkina Faso; a popular shopping area in Jakarta, Indonesia; and Sultanahmet Square, the historic and cultural heart of Istanbul.

Seemingly uncoordinated, the indiscriminate violence highlighted the goal of Islamist militants determined to sow terror in disparate corners of the world. At the same time, the United Nations reported on Tuesday that more than 19,000 Iraqis died in a 22-month period marked by what it called a “staggering” level of violence.

In the year since gunmen killed 12 people in Paris in an attack aimed at Charlie Hebdo, a satirical weekly newspaper that had lampooned Islam, jihadis have embarked on an ever-widening campaign of global bloodletting that would appear to have little strategic value.

The attacks also highlight the growing rivalry between followers of the Islamic State and al-Qaida, extremist organizations determined to prove their jihadi bona fides through a gruesome tally of random bloodshed.

In Baghdad and nearby Diyala province, Islamic State assailants last Monday killed at least 40 people in twin attacks that targeted ordinary Iraqis as they shopped and relaxed at a cafe. In Jakarta on Thursday, gunmen fatally shot the audiologist, Tahar Amer-Ouali, who had spent much of his life helping the hearing-impaired. In Ouagadougou, the dead included Westerners and Africans, Muslims and Christians.

Maude Carrier, 37, a high school French teacher from Quebec and the mother of two girls, was among those killed by al-Qaida gunmen on Friday as they sat in the Cappuccino Cafe, a popular spot in downtown Ouagadougou.

Also killed were Carrier’s father, Yves; his current wife, Gladys Chamberland; and the couple’s 19-year-old son, all members of an aid mission that was sprucing up schools in Burkina Faso, a former French colony.

“They did things like fix roofs and repaint blackboards,” Camille Carrier, Maude Carrier’s mother, told The Globe and Mail, a Toronto newspaper. “Who would want to kill people fixing blackboards?”

Some members of the group, most of them educators, had taken two or more trips to Africa coordinated by two organizations in Quebec.

“They fell in love with Burkina Faso,” said Sister Yolande Blier of the Congrégation des Soeurs de Notre-Dame du Perpétuel Secours near Quebec City, one of the groups that helped coordinate the excursions, according to The Canadian Press news agency. “They loved the values of the Burkinabe; they loved the welcome there.”

On Facebook, Carrier reveled in the experience, posting a photograph of herself beaming as she held aloft an infant (“I found my baby,” she wrote) and a group shot taken in front of a blackboard with a message that read, “Education is true freedom!”

A predominantly Muslim country, Burkina Faso had until last week escaped the jihadi violence that has plagued its neighbors, Niger and Mali, where an Islamic State attack in November killed at least 19 people at a luxury hotel in Bamako, the capital.

In a Facebook posting, Chamberland, Carrier’s stepmother, sought to play down the threat of terrorism in the region.

“Your chances of dying because of terrorism is 1 in 116 million,” she wrote, adding a reference to the national lottery in Canada, “You are 10 times more likely to win the 6/49.”

Survivors in Ouagadougou said the militants who attacked the cafe and a nearby hotel had chosen their victims indiscriminately, although they reportedly fired off extra rounds into the bodies of Westerners.

Among the dead were Arie Houweling, 67, a Dutch consultant who advised entrepreneurs in Burkina Faso and Niger; Leila Alaoui, 33, a French-Moroccan photographer; and Michael James Riddering, 45, an American missionary from Florida who worked at an orphanage outside the capital.

“My best friend, partner in crime and love of my life,” Riddering’s wife, Amy, wrote on her Facebook page. “The best husband ever. An amazing father to his children and a papa to everyone.”

The other victims of the attacks carried passports from France, Libya, Portugal and Switzerland. But many of them, like Victoria Yankovsky, a Ukrainian who ran the Cappuccino Cafe, considered themselves global citizens.

“Their employees adored them and some even followed them to new places, which is quite uncommon in Africa,” said Katerina Zolotaryova, a friend of Yankovsky, who died alongside her husband and 9-year-old son. “It is a shock because usually terrorists don’t attack such common, average people, who are not connected to politics or anything sensitive.”

The dead also included at least seven citizens of Burkina Faso; among them were Simplice Armel Kinané, a firefighter who worked for an air safety organization, and Ahmed Kéré, a local coordinator for a U.S. nonprofit group.

Kinané, according to his sister, was attending a poolside reception at the Splendid Hotel when attackers set off an explosion outside the building and then stormed inside. She said her brother had been shot as he tried to put out the flames that had engulfed a hotel guest.

“He was generous and supportive to the point of giving his life in exchange,” the sister, Yolande Kinané, said. “He was our protector, our defender.”

Those who knew Kéré, who worked for the Sonder Project, an antipoverty group based in Florida, described him as a gentle, exuberant man who worked on local school-building projects and helped Western volunteers with translations.

Ian Vardy, a Canadian who spent eight days with Kéré on a trek to a remote village last August, recalled his zeal for helping others. “He was like many Burkina Faso people; selfless, kind, eager to convey joy and love,” Vardy wrote in an email exchange. “They believe in the concept that we all need each other, because traditionally for years, they have. These are the richest people, and they have no money.”

Some victims had tried to start over after fleeing conflict. Among the dead in Baghdad was Amir Mishaan, 45, a father of three who had gone to the capital last year after Islamic State fighters seized his hometown, Ramadi.

Halfway across the world, in Indonesia, the Islamic State militants who set off explosive devices outside a Starbucks in Jakarta last Thursday appeared to single out foreigners. Amer-Ouali, 70, a Canadian citizen born in Algeria, operated several hearing-aid clinics in the Montreal area. His brother was among the 22 people wounded in the attack.

Amer-Ouali split his time between Montreal and Jakarta, where he ran a clinic called the International Hearing Center.

In an interview with the Canadian broadcaster CTV, a son of Amer-Ouali described him as an avid mountain climber who had fallen in love with Indonesia.

“That was an area of the world he really enjoyed. He was helping deaf people,” the son, Farid Amer-Ouali, said, adding, “He was looking to reach out to people over there, looking for opportunities to try to give them the care they have here.”

In Istanbul last Tuesday, the suicide bomber who waded into the throngs near the Blue Mosque and the Hagia Sophia appeared to have chosen a group of German tourists who had arrived in Turkey a day earlier. The Turkish authorities say the attacker, a Syrian in his late 20s, was an Islamic State operative.

Most of the 10 people killed in the explosion he set off were middle-class retirees: One had been a butcher, another a teacher, another a construction manager.

The dead included a father and son from Dresden, Gunther Hoppner, 75, a retired waiter, and Steffen Hoppner, 51, who worked at a Volkswagen factory. “All this is so senseless and impossible to comprehend right now,” Petra Hoppner, Steffen’s wife, said by telephone. “I’m speechless and devastated. My husband took his dad on that trip because my father-in-law was very much interested in historic sites.”

In a Facebook posting, the daughter of Karin Franke-Dutz, the retired teacher from Leipzig who was also killed in Istanbul, recalled the anxiety she felt over her mother’s decision to join a tour that would take her to Turkey as well as Dubai and Abu Dhabi, both in the United Arab Emirates. “I had an exchange of messages with my mother until late at night,” the daughter, Birgit Franke, wrote on Facebook.

“Finally, I wrote the sentence, ‘Why do you pick such destinations?’” she said. “Then I thought about it, erased it and wrote, ‘Good luck!’ Those were my last words.”

© 2016 The New York Times Company