The military has opened an investigation into Saturday's devastating helicopter crash in eastern Afghanistan that killed 30 U.S. troops and eight Afghans.

Pentagon officials would not discuss the details of the probe, but it will no doubt address a host of questions surrounding the crash, including a look at the insurgent threat and the instructions given to the special operations team crowded into the Chinook helicopter as it raced to assist other U.S. forces.

According to officials, the team, which included 22 Navy SEAL personnel, three Air Force troops, a five-member Army air crew and a military dog, was flying in to help U.S. Army Rangers who were going after insurgents on the ground. Seven Afghan commandos and an Afghan interpreter were also on board.

The helicopter apparently was shot down by an insurgent armed with a rocket-propelled grenade. It was the single deadliest loss in the decade-long war.

Gen. James Mattis, head of U.S. Central Command, has appointed Army Brig. Gen. Jeffrey Colt to lead the investigation. Colt is deputy commander of the 101st Airborne Division at Fort Campbell, Ky.

The investigation comes as the remains of the troops killed in the deadliest incident of the Afghan war came home Tuesday — shrouded in secrecy by a Defense Department that has refused so far to release the names of the fallen and denied media coverage of the arrival at Dover Air Force Base in Delaware.

Two C-17 aircraft carrying the remains of the 30 U.S. troops killed the crash arrived late Tuesday morning and were met by President Barack Obama, Defense Secretary Leon Panetta, Joint Chiefs Chairman Adm. Mike Mullen and a number of other military leaders.

The helicopter crashed as it attempted to land in the Tangi Valley, a dangerous region in Wardak province, where coalition forces were engaged in a firefight with insurgents. The mission was targeting a Taliban leader believed to be in the mountainous and militant-riddled Sayd Abad district of Wardak.

The investigation will review a number of basic crash questions, more likely to rule out things like the weather, terrain and mechanical issues, since military officials believe the helicopter was shot down.

It will then also look at the altitude and flight path of the Chinook as it moved into the fighting zone. Chinooks are heavy cargo helicopters that do not have the agility of smaller, more maneuverable aircraft.

There also will be questions about why that team was called in, what they knew about the situation on the ground and what protections they may have had against fire from the ground.

At the Pentagon, officials wrangled over whether to release the identities of any or all 30 Americans who died in the crash, even though many of the families have publically named their loved ones and spoken openly about their deaths.

It has consistently been department policy to release the names of troops who are killed.

Several officials said privately there is hesitancy to release the names because the majority were from secretive special operations forces, including 22 U.S. Navy SEAL personnel. Some have said there is a worry that terrorists will target the families, because many of the SEALs were from the same team that killed Osama bin Laden in May.

None of those killed participated in the bin Laden raid, senior defense officials said.

Panetta is expected to make the final call on the release of the names, but Pentagon officials could not say Tuesday when that decision is expected.

The somber arrival of the remains at Dover, while witnessed by many senior officials and family members, was not covered by the media.

Pentagon spokesman Col. Dave Lapan said the reason the media were not allowed to view the military's "dignified transfer" ceremony was because the badly damaged remains are mingled and not all identified.

Usually, the families of the deceased are allowed to determine whether there will be press coverage.

But the Pentagon said in a statement this week that that "due to the catastrophic nature of the crash, the remains of our fallen service members will be returned ... in 'unidentified' status until they can be positively identified by the Armed Forces Mortuary Affairs Office at Dover. Because the remains are unidentified at this point, next-of-kin are not in a position to grant approval for media access to the dignified transfer."

Officials at Dover watched as 30 transfer cases draped in American flags and eight draped in Afghan flags were taken off the two planes. There were several additional transfer cases on the plane, also carrying unidentified remains from the crash.

The Dover ceremony took several hours due to the number of caskets, which are taken off the plane individually in a slow, somber ceremony with honor guards.

An 18-year ban on media coverage of the returns at Dover was lifted in 2009 by then-Defense Secretary Robert Gates, leaving the decision to the families of the war dead.

Several news organizations have protested the Pentagon decision to prohibit coverage Tuesday.