The U.S. military blamed the crew of a Marine jet Thursday for an accident that killed 20 people aboard a ski gondola, saying the jet was flying too low and too fast when it sliced through the gondola's cable.

The crew as well as supervisors now face disciplinary action, including a possible court-martial for involuntary manslaughter or negligent homicide."The cause of the mishap was air crew error," the military said in a report, read by Maj. Gen. Michael DeLong, president of the accident investigation board.

"The air crew aggressively maneuvered their aircraft, exceeded the maximum air speed and flew well below" the allowed limit, it said.

The EA-6B Prowler, flown by a four-man crew from the United States' Aviano base, severed a cable on the ski lift in northern Italy on Feb. 3, sending 19 skiers and the cable car operator to their deaths on the valley floor below.

Lt. Gen. Peter Pace, commander of Marine forces in the Atlantic region, said that he agreed with the findings of the board to refer the case for a pretrial investigation - the equivalent of a civilian grand jury.

Pace said he wanted the inquiry to consider possible charges of involuntary manslaughter, negligent homicide and dereliction of duty.

He also recommended action against supervisory officers for allegedly failing to inform flight crews that the actual altitude limit was 2,000 feet - not 1,000 feet as the supervisors had told the crew.

The report said the jet was about 370 feet off the ground when it hit the cable.

The Marines had said from the outset that the plane was flying dangerously low, but Thursday was the first time they blamed it on the crew and not on possible mechanical problems.

Pace said the United States should "pay all proper claims for death and property damage arising from this incident."

"I have taken these actions to ensure accountability for those responsible, to obtain restitution for those who merit it and to prevent similar tragedies," Pace said.

He said they flew "lower and faster" whenever the terrain allowed it, meaning whenever there was a valley.

Investigators said they found no evidence the crew's action was part of a pattern, nor did they give an explanation.

"I have no idea or what they thought or what they were thinking about," DeLong said.

Italian Prosecutor Francantonio Granero said he would press ahead in his own criminal investigation, although Italy has acknowledged there was little likelihood the Marines would surrender the crew for prosecution here.

Officers said the four crew members refused to talk to investigators on the advice of their lawyers, submitting only written statements.

The crew of the Prowler has been grounded since the accident.