AMMAN, Jordan >> A Jordanian policeman opened fire Monday on foreign trainers at a police compound, killing two Americans, a South African and a Jordanian before being shot dead, the Jordanian government said.

The attacker also wounded two Americans and three Jordanians, said spokesman Mohammed Momani.

Authorities have launched an investigation into whether the motive for the shooting was personal or political, said Momani.

A military official said the attacker was a police captain who worked as a trainer at the facility. The captain was married and had two children, said the official, who spoke on condition of anonymity because the government has not released the assailant’s identity.

A U.S. official said the Americans who were killed and wounded in the attack were part of a State Department police training program. The official said all were civilians, but declined to identify them. The official wasn’t authorized to speak publicly on the matter and demanded anonymity.

Momani said the Jordanian killed in the attack was a civilian employee at the center.

About two hours after the shooting, dozens of armored vehicles were moving in and out of the large, walled training center on the outskirts of Amman. The center was established in 2003, and has trained 53,000 police officers from Iraq, 8,000 from the Palestinian territories and additional groups from other Arab countries, according to its website.

Jordan, a close U.S. ally that has a peace treaty with Israel, has long been seen as an island of relative stability in a turbulent region.

Over the past year, the pro-Western kingdom has taken on a high-profile role in the fight against extremists, including the Islamic State group, which controls large areas of neighboring Iraq and Syria.

There has been concern that militants could carry out revenge attacks on Jordanian soil.

“We have full confidence in our security measures, and the investigation will uncover the motivation behind what happened,” Momani told The Associated Press. In an earlier statement, he referred to the shooting as a crime.

In Washington, State Department spokesman John Kirby said U.S. officials were “in contact with the appropriate Jordanian authorities, who have offered their full support.”

U.S. forces in Afghanistan have come under attack on a number of occasions by local police and troops serving alongside them, in what are known as “green-on-blue” assaults. Such attacks have been extremely rare in the Middle East.