U.S. Central Command said it is investigating a video posted online that appears to show a U.S. servicemember firing at a civilian truck driver in Afghanistan.

The U.S. military is investigating a video posted to YouTube that appears to depict a U.S. servicemember opening fire on a civilian driving a truck in Afghanistan, U.S. military officials said.

The video, apparently recorded on a camera attached to a servicemember's helmet, shows a servicemember holding a shotgun as his military vehicle passes the truck. The side window of the truck shatters, though it is not clear that a round from the shotgun was fired.

The clip, first reported by Politico on Wednesday night, has prompted an investigation by U.S. Central Command, which oversees military operations across the Middle East and parts of South Asia. Defense Secretary Jim Mattis is aware of the case, said Dana White, a spokeswoman for the secretary.

"We actually have very good procedures for this, as you know," Marine Lt. Gen. Kenneth F. McKenzie Jr., the director of the Pentagon's Joint Staff, told reporters Thursday. "We take these allegations very seriously. ... This is not something we look at lightly, and it'll receive all the serious attention that it deserves."

CENTCOM said in a statement that the video is not official, not authorized and does not represent the professionalism of U.S. troops.

"I have reviewed the video and I am disappointed and also concerned that the American people, our Coalition partners, the Afghan government, and the Afghan people will believe that American servicemembers are callous and indifferent to the horrors of war or the suffering of innocent people trapped in conflict," said Army Gen. Joseph Votel, the chief of CENTCOM, in the statement. "I can assure you that this video does not represent the professionalism or humanity of the men and women of U.S. Central Command. We reject the unprofessional and callous message this video conveys."

Politico reported that the video was initially posted anonymously under the title "Happy Few Ordnance Symphony" and quickly removed. It could mark yet another in a long line of instances in which U.S. troops have photographed or recorded video of themselves or their colleagues misbehaving in war zones, only to face criminal or administrative discipline afterward.

The video shows the servicemember carrying the shotgun wearing a pattern of camouflage often associated with Special Operations troops, though it isn't clear whether any were involved in the incident. It also isn't clear whether the shotgun was loaded with lethal ammunition or a nonlethal alternative such as a beanbag, which U.S. troops sometimes carry.

Servicemembers regularly shoot videos and photos, and YouTube is home to many videos recorded in combat. The U.S. military prohibits service members from taking photographs or video with detainees or human remains.