The U.S. military is investigating photos that appear to depict Marines burning the bodies of dead Iraqi insurgents in the western Iraqi city of Fallujah in 2004, a Pentagon spokesman said Wednesday.

The photos were obtained by the gossip and entertainment Web site TMZ, which published some of them Wednesday. It said others were withheld because they are “just too gruesome.”

Two of the photos show a Marine apparently pouring a flammable liquid on two bodies. Other shots show the remains on fire and, after the flames went out, charred. A Marine in another photo is shown apparently rifling through clothing amid one corpse’s skeletal remains. Another Marine is shown posing in a crouch with his rifle pointing toward a human skull.

“We are aware of photos appearing on that depict individuals in U.S. Marine uniforms burning what appear to be human remains,” Navy Cmdr. Bill Speaks, a Pentagon spokesman, said in a statement. “The actions depicted in these photos are not what we expect from our service members, nor do they represent the honorable and professional service of the more than 2.5 million Americans who have served in Iraq and Afghanistan.”

Speaks said the Marine Corps “is currently investigating the veracity of these photos, circumstances involved, and if possible, the identities of the service members involved.” He said the findings from that inquiry would “determine whether we are able to move forward with any investigation into possible wrongdoing.”

TMZ said on its Web site that it obtained 41 photos reportedly taken in Fallujah in 2004. It said more than a dozen bodies were shown in the photos, “and some are covered with flies and one is being eaten by a dog.” TMZ said it turned over all the photos to the Pentagon last week. Eight of the photos were published on the Web site Wednesday.

The U.S. Central Command, which directs military operations in the Middle East, determined that the photos had not been previously brought to its attention, TMZ reported.

Fallujah, a city in Anbar province in western Iraq, has been the scene of three-way fighting in recent weeks pitting a rejuvenated force affiliated with al-Qaeda against local tribes and Iraqi government forces. The al-Qaeda-linked militants claimed to have captured Fallujah on Jan. 3, raising their flag over government buildings and declaring an Islamic state in one of the most crucial areas that U.S. troops fought to pacify before withdrawing from Iraq two years ago.

Fallujah was where Marines fought the bloodiest battle of the Iraq war, ultimately taking control of the city. Nearly 100 U.S. troops were killed there in November 2004 in the military’s deadliest battle since the Vietnam War. Roughly a third of the 4,486 U.S. troops killed in Iraq died in Anbar province trying to defeat al-Qaeda in Iraq.