A Jordanian army officer shot dead two American military personnel and one South African and wounded six other people on Monday at a U.S.-funded security training facility near Amman, Jordan's government spokesman said.
Mohammad Momani told Reuters that the attacker was shot dead by Jordanian security forces; he did not commit suicide as security forces earlier reported.
A Jordanian security source said the gunman was a senior co-trainer with the rank of captain.
The incident occurred in a facility that mainly trains Iraqi and Palestinian forces on the outskirts of the capital Amman.
It took place on the 10th anniversary of al Qaeda suicide bombings that targeted three Amman luxury hotels and killed dozens of people in the worst militant attack in the history of Jordan, a staunch U.S. ally.
Jordan is now part of the Washington-led coalition that is trying to defeat Islamic State insurgents that have seized large tracts of Syria and Iraq, both of which border Jordan.
The country hosts several hundred U.S. trainers who are part of a military program to bolster the kingdom's defenses, including the stationing of F16 fighter jets that use Jordanian airfields to hit Islamic State positions in neighboring Syria.
But the kingdom's role in the war against Islamic State has raise disquiet among some Jordanians about instability at their borders. They fear that Jordan's stepped-up role in the campaign might lead to Islamist attacks in their country.
King Abdullah believes fervently that ultra hardline jihadists pose an existential threat to the kingdom.