Eight people have died in an attack on a police training facility near Amman, Jordan, with another six injured, three U.S. government sources told Reuters on Monday.The gunman's motive for opening fire at the U.S.-funded security training facility were not immediately known and one of the U.S. sources cautioned that the situation is very fluid. So far, two Americans, a South African and three Jordanian and the attacker himself reported dead. In the mean time, Jordan's government spokesman on Monday denied U.S. assertions that eight people had been killed in a shooting on Monday in a police training centre in the Jordanian capital, saying the latest death toll was still five, including the Jordanian attacker."Only five are dead, including two Americans, a South African, a Jordanian, and the attacker," said spokesman Mohammad al Momani. He said one of the wounded was in critical conditionAuthorities have launched an investigation into whether the motive for the shooting was personal or political, said spokesman Mohammed 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.