UPDATE: 2:22 p.m. EDT -- Three U.S. military trainers were shot dead Friday by Jordanian security forces who claim the vehicle carrying the U.S. personnel failed to stop at the entrance of Prince Faisal Air Base near the southern Jordanian city of Al-Fajr. 

"The intial report is that they came under fire as they were the facility in vehicles. We are working closely with the government of Jordan to determine exactly what happened," Pentagon Press Secretary Peter Cook said in a statement.

UPDATE: 11:51 a.m. EDT -- Three U.S. personnel  were shot dead Friday by Jordanian security forces after their vehicle failed to stop at the entrance of Prince Faisal Air Base near the southern Jordanian city of Al-Jafr, according to U.S. officials. Earlier reports had claimed two U.S. trainers had been killed.

Original Story:

Two U.S. military trainers were shot dead Friday by Jordanian security forces after their vehicle failed to stop at the entrance of Prince Faisal Air Base near the southern Jordanian city of al-Jafr, Al Jazeera reported.

"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," a Jordanian military source told Reuters.

The attack, which wounded an additional U.S. and Jordanian officer, did not appear to intentionally target U.S. forces, CBS News reported. The U.S. Embassy has reportedly communicated its knowledge of " a security incident involving U.S. personnel” and confirmed it was working with Jordanian authorities to investigate the incident. The injured have been evacuated from the scene for medical treatment, according to Jordanian news outlet Al-Rai.

The U.S. and Jordan are military allies and have cooperated in the war against the Islamic State group, an extremist militant group active in neighboring Iraq and Syria. In May, the two nations held a massive joint military exercise known as Operation Eager Lion. The U.S. has also offered assistance in receiving Syrian refugees and training Iraqi and Palestinian security forces in Jordan. The U.S. announced last year an increase of over 50 percent in aid to Jordan, amounting in $1 billion annually.

Two U.S. private military trainers were killed in 2015 along with a South African and two Jordanians when a Jordanian police officer opened fire at a police training center east of Amman. Jordanian authorities blamed the attack on the perpetrator's mental instability and did not link it to terrorism.

The Prince Faisal Air Base, also called the King Feisal Air Base, in al-Jafr hosts military instruction from a number of countries including the U.S., according to Agence France-Presse.