AMMAN- Reuters, 04 Nov. 2016- Three U.S. military trainers were shot dead in Jordan on Friday when their car failed to stop at the gate of a military base and was fired on by Jordanian security forces, a Jordanian military source said.

The incident occurred at the Prince Faisal air base in the south of the country, a close ally of the United States. Two trainers died immediately and a third died later in hospital.

A Jordanian army guard was also shot and wounded.

Three US military trainers killed at al-Jafr air base

“There was an exchange of fire at the entrance to the base after an attempt by the trainers’ vehicle to enter the gate without heeding orders of the guards to stop,” the military source said.

“An investigation is now under way to know exactly what happened.”

Another Jordanian security source said it was not possible to rule out political motives in the incident at an air base where dozens of U.S. trainers work alongside Jordanians.

U.S. officials, speaking on condition of anonymity, told Reuters they were reviewing the incident and could not rule out the possibility of a deliberate attack.

One said there were Americans in the convoy who were unharmed in the incident.

A Pentagon spokesman confirmed the shooting incident.

“We are saddened to report that three U.S. service members were killed today in a shooting incident at a Jordanian military base,” Peter Cook said, adding more information would be provided “as appropriate”.

Jordan hosts several hundred U.S. contractors in a military programme which includes the stationing of F-16 fighter jets that use Jordanian airfields to hit Islamic State positions in neighbouring Syria.

Since the start of the Syrian conflict in 2011, Washington has spent millions of dollars to help Jordan set up an elaborate surveillance system known as the Border Security Programme to stem infiltration by militants from Syria and Iraq.

U.S. officials say aid to Jordan, one of the largest recipients of U.S. foreign military assistance, is expected to rise to $800 million in 2016 and grow in future years.