All three Marines shot to death Friday by a man dressed as an Afghan police officer in Helmand province have been identified as being with Camp Pendleton's 1st Marine Special Operations Battalion.

Gunnery Sgt. Ryan Jeschke, 31, of Fairfax, Va., and Staff Sgt. Sky R. Mote, 27, of El Dorado, were killed in the attack, along with team leader Capt. Matt Manoukian, 29, of Los Altos Hills, the Marine Corps said Monday.

According to initial reports, the three were killed at a security meeting, following an early-morning meal with the Afghan police officer. The Taliban and the district chief of Sangin district of Helmand province identified the assailant as a member of the Afghan National Police who was helping Marines train the Afghan local police.

A member of the special operations team and a close friend of the dead Marines, however, on Monday recounted a sequence of events in conflict with the earlier reports. The Marine, who is not authorized to speak publicly, based his account on five eyewitnesses.

He said the gunman was dressed as a member of the Afghan local police rather than the national police, and that the Marine operators were not lured to a checkpoint or an Afghan home. He said the three were shot to death at their military operations center.

The Marines had just finished an early morning shura security meeting at their military outpost when an Afghan man appeared unescorted at the door to their tactical operations center, he said. Only trusted Afghans are allowed into the inner sanctum of the base, and always with an escort.

After the Afghan man was challenged, he grabbed a rifle and shot Jeschke in the back and continued shooting through the thin plywood into the operations center, fatally wounding Manoukian and Mote. He then burst into the tactical operations center and shot Manoukian and Mote again at close range, the source said.

A fourth Marine was shot in the arm but is on his way home for treatment and expected to survive his wounds.

It remains unclear whether the gunman was in fact a member of the 120-strong local police force in Puzeh or had merely obtained one of their uniforms.

The shooting, at about 2 a.m. Friday, is under investigation, said Master Sgt. Jonathan Cress, spokesman for Special Operations Taskforce-West, declining to comment further.

The "green-on-blue" assaults by Afghan security force members on their international counterparts have cast a shadow over U.S. efforts to train Afghan soldiers and police. There were two more such attacks on Monday, officials said.

Navy SEALs and more Marine special operators from the team who were working elsewhere are reinforcing the remaining coalition force at Puzeh so they may continue their mission stabilizing security around the village and fostering governance and economic development.

Jeschke, interviewed in Afghanistan by U-T San Diego in late July, described how Marine special operations forces, like those from other branches, can have a greater impact by working in smaller numbers more closely with Afghan forces. That proximity and the difficulty of determining whom to trust amid an insurgency also puts special operations forces at extreme risk.