FREETOWN, Sierra Leone – A U.N. helicopter crashed in Sierra Leone (search) on Tuesday, killing all 24 peacekeepers, aid workers and others on board, a U.N. spokeswoman in the West African nation said.
Victims aboard the Russian-made Mi-8 also included the Russian crew, U.N. mission spokeswoman Sharon McPherson said.
There was no immediate word on the cause of the crash. Russia's Itar-Tass news agency said the wreckage was in flames after the crash.
The United Nations (search) has about 11,800 peacekeepers in Sierra Leone overseeing the country's peace accord after a 1991-2002 civil war. There have been no known attacks on U.N. officials since.
The helicopter had taken off from Freetown, Sierra Leone's capital, with 21 passengers and three crew members, said Daniel Adekera, another U.N. spokesman.
Passengers included peacekeepers and other U.N. personnel, aid workers and other civilians, Adekera said.
It was bound for the western city of Kailahun, he said.
Ground crew lost radio contact with the aircraft and sent a search mission seven minutes later, Adekera said.
Helicopters are the main method of cross-country transportation in Sierra Leone, where there are few good roads. The white, dual-rotor U.N. helicopters lift off frequently from a helipad in the U.N. headquarters in Freetown, ferrying peacekeepers, relief workers and supplies.
In New York, U.N. Secretary-General Kofi Annan's (search) office said the United Nations had opened an investigation into the crash.
"The secretary-general extends his deep condolences to the families and governments of those who have perished in this tragedy," a statement released by Annan's office said.
"He once again pays tribute to the men and women who have lost their lives in the name of peace in this and other important peacekeeping operations."
ITAR-Tass said the helicopter was flown under contract with the United Nations.