A Jordanian police officer opened fire on foreign trainers at a U.S.-backed training center for security officers from across the Middle East, killing two Americans and a South African before being shot dead.

In addition to those killed, two Americans and four Jordanians were injured, one of whom is in critical condition, during the shooting at the compound, located near the Jordanian compound of Amman, according to the Associated Press.

Minister of State for Media Affairs Mohammad Al Momani spoke to state media about the incident, saying the shooting has been labelled a "crime," noting that an investigation has been launched.

A motive behind the shooting is unknown and there are conflicting reports about what happened during the incident. Some local media outlets suggest that the shooting was "accidental" while others report an exchange of fire between the Americans and the Jordanian officer, according to The Guardian.

"It is not yet known whether the shooting was because of a dispute between the policeman and the contractors," one official was quoted saying.

While the cause of the shooting may still be unknown, the incident does fall on the 10th anniversary of a series coordinated attacks by al-Qaeda in Iraq that killed 60 people and injured more than 100, and bears strong similarities in Afghanistan in which guns were turned on U.S. trainers, according to the Washington Post.

The U.S. Embassy has yet to comment on the incident.