MONROEVILLE, Pa. » A teenager who police say opened fire at a Pittsburgh-area mall, shooting his intended target as well as a couple, was arrested early Sunday after police used surveillance footage and an Instagram photo to link the suspect to the shooting.

Gunfire erupted inside the men’s department on the lower level of Macy’s department store at the Monroeville Mall about 7:30 p.m. Saturday (2:30 p.m. Hawaii time), sending panicked shoppers running. The gunman fled but police say they were able to identify him by matching surveillance video with an image of the suspect on Instagram, according to the criminal complaint.

Tarod Thornhill, 17, was arrested at a home in Brackenridge about 3:15 a.m. Sunday. He was being held at the Allegheny County Jail pending arraignment on charges as an adult of aggravated assault, attempted homicide and recklessly endangering other people. A preliminary hearing was scheduled for Feb. 18, according to court documents.

Police Chief Douglas Cole said two men and a woman were shot, including the man who was targeted.

"This was not random," Cole told reporters. "We have evidence that leads to that." He declined to elaborate.

Thornhill’s intended target, 20-year-old Davon Jones, was in critical condition, Forbes Hospital spokesman Jesse Miller said. The two bystanders, Thomas and Mary Singleton, were listed in critical and fair condition, respectively.

According to the complaint, Thornhill can be seen on surveillance video approaching Jones with a gun at his side and exchanging words with him. As the Singletons and their son walk in between the two, Thornhill begins firing "indiscriminately."

After the victims were brought to the hospital, it went on lockdown until 3:42 a.m. Sunday, Miller said.

The stores were open Sunday, except for one. By the evening, the mall had announced it would institute a "Youth Escort Policy" that would bar unaccompanied minors from the mall on weekend nights.

The policy will go into effect at the end of February and apply to the hours after 6 p.m. on Friday and Saturday. Anyone under the age of 18 must be accompanied by a parent or guardian who is at least 21 years old. Teens who work at the mall during those times will be issued identification.

"The conduct of unsupervised youth and young adults at Monroeville Mall has created an uncomfortable atmosphere for mall visitors and an increasing safety challenge," the announcement said.

In late December, hundreds of teenagers gathered at the mall and several fights broke out. The fights caused local officials and mall administration to agree on a plan to increase security there. Police plan to have an increased presence at the mall, said Stacey Keating, a spokeswoman for the mall.

Pennsylvania native and ex-NFL quarterback Terrelle Pryor tweeted Saturday that he was at the mall, a short drive east of Pittsburgh, when the shooting occurred.

"Damn was just in monroeville mall and just saw 2 ppl get shot," he tweeted. "They are letting guns go in there."

Police went store to store to evacuate the mall, and shoppers described chaos as shots rang out.

"All of the sudden we heard people screaming," Athena Coffey of Churchill told KDKA-TV, "and the next thing you see is a bunch of people, teenagers, scared to death, just exodus en masse in a way you could not believe. I grabbed my children, husband, we started screaming ‘go, go, go!’"

Yvette Jackson of North Braddock was attending a birthday party at Giggles andSmiles, a fitness and fun center for children.

"We saw a lot of running, a lot of chaos," she told the Pittsburgh-Tribune Review. She said she and other patrons were locked in the store for about 45 minutes until police came and let them out.

The mall, which is owned and managed by CBL & Associates Properties Inc., of Chattanooga, Tennessee, has 1.1 million square feet of shopping space. It says on its website it features more than 125 stores and eateries, anchored by JCPenney, Macy’s and Barnes & Noble.