WASHINGTON - US President Barack Obama on Tuesday participated in a ceremony in Dover Air Force Base in Delaware, honoring Navy SEALs and other servicemembers died in a helicopter shot down in Afghanistan, the White House and the Defense Department said.

Obama traveled to the base on helicopter shortly after noon. Upon arrival at Dover, he was taken down the tarmac to where two C-17 cargo planes containing the remains of the fallen servicemen were located. Obama was then escorted to the first plane. He boarded the plane with his military aide and spent time on board paying his respects. He then walked around 100 yards to the second C-17, boarded it with his military aide, and spent time on board paying his respects, according to a White House official who spoke on background.

The planes carried back remains of 30 US servicemembers, whose CH-47 Chinook helicopter was shot down by a Taliban rocket propelled grenade on Saturday - the most deadly single attack since the beginning of the Afghanistan war in 2001.

After paying his respect, Obama was motorcaded to a building in the base where approximately 250 family members and fellow servicemen and women of the fallen had gathered. He spent approximately 70 minutes meeting them, offering condolences and gratitude.

Alongside Obama, Defense Secretary Leon Panetta was also in attendance at Dover, as was Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, and Michael Vickers, undersecretary of defense for intelligence, according to the Pentagon.

The White House didn't announce Obama's participation in the ceremony beforehand. The president cancelled a previously scheduled visit elsewhere earlier in the day, and instead went to take part in the ceremony.

The incident came just over a month before the tenth anniversary of the "9/11" attacks. Pentagon hasn't released the names of those killed in the incident, among them 22 Navy SEALs, three Air Force special operations ground controllers and five Army helicopter crew members. The SEALs belonged to Team Six, the elite unit that was responsible for the killing of Osama bin Laden in a raid in Pakistan over two months ago. Seven Afghan commandos and an Afghan interpreter were also killed.

According to the military, the remains of the servicemen were not able to be easily identified because of the damage done in the crash. The remains will be identified by the mortuary team through DNA, dental records and fingerprints. The remains were seen to be carried off the plane in flag-covered cases.