Weapons provided by the Central Intelligence Agency that were supposed to go to Syrian rebels have found to be “systematically stolen” and sold on the black market, according to the New York Times.

But according to officials, those weapons have also been used to kill Americans.

FBI officials believe that two of the weapons, which were stolen by Jordanian intelligence operatives, were used in the shooting in Amman that killed five people, including two American contractors, in November, the Times reported.

Rebel fighters with the  Jaish al-Islam (Army of Islam) learn self-defense during a training session in Eastern al-Ghouta, a rebel-held region outside the capital Damascus on January 11, 2015. Syria's conflict began as a pro-democracy revolt that later morphed into a brutal civil war after President Bashar al-Assad's regime unleashed a brutal crackdown against dissent. AFP PHOTO/ ABD DOUMANY        (Photo credit should read ABD DOUMANY/AFP/Getty Images)

Rebel fighters with the Jaish al-Islam (Army of Islam) learn self-defense during a training session in Eastern al-Ghouta, a rebel-held region outside the capital Damascus. Syria’s conflict began as a pro-democracy revolt that later morphed into a brutal civil war after President Bashar al-Assad’s regime unleashed a brutal crackdown against dissent. (Getty Images/Abd Doumany)

Both American and Jordanian officials told the Times that investigators believe the weapons used in the November shooting were weapons that were originally intended for the Syrian rebel-training program. Those officials said they used the serial numbers on the weapons in order to make that determination.

The FBI’s investigation into the shooting is ongoing.

Due to the theft of the weaponry and subsequent resale on the black market, a bevy of new weapons have been made available on the black market for purchase by criminal organizations, weapons smugglers and Jordanian tribes. However, the Times reported that investigators are unsure what has happened to most of the weapons, which include mortars, rocket-propelled grenades and Kalashnikov assault rifles.

“The United States deeply values the long history of cooperation and friendship with Jordan,” State Department spokesman John Kirby told the Times. “We are committed to the security of Jordan and to partnering closely with Jordan to meet common security challenges.”

Read more of the New York Times’ findings here.