BAGHDAD, Iraq — A U.S. military helicopter crashed north of Baghdad today, but there was no word on the status of the two-man crew.

There was no word on the cause of the crash. The military said only the helicopter went down around 8:20 a.m.

Helicopters used by the Army that have a two-person crew include the AH-64 Apache and the OH-58 Kiowa reconnaissance.

The number of fatal U.S. military helicopter crashes in Iraq has shot up in recent weeks, fitting a wartime pattern of more frequent accidental and combat crashes during winter months.

Also today, a car bomb detonated next to a police convoy and killed six people, including a six-year-old child and five police officers, a police operations center and hospital said.

The car blew up in Muqdadiya, about 60 miles north of the capital, a police joint operations center and a local hospital said.

Najim Abid, a medic at Muqdadiya general hospital, said five policemen and a child were killed by the blast, which injured sixteen civilians and three policemen.

KABUL, Afghanistan — Afghanistan's president urged nations not to turn their back on his country four years after the ouster of the radical Taliban, warning it could again be used as a staging post for terrorists to attack Europe and America.Speaking at his palace in Kabul ahead of a foreign donors' conference in London later this month, President Hamid Karzai said his nation will need assistance for a long time."We are in a joint struggle against terrorism, for us and for the international community," he told reporters. "If you don't defend yourself here, you will have to defend yourself back home, in European capitals and Americans' capitals.""We take losses, Afghans die, the international community gives life for a common cause, for the safety of the world," he said.His comments came a day after a senior Canadian diplomat was killed along with two Afghan civilians in a suicide car bombing in Kandahar city, a former stronghold of the Taliban in the south.The violence has undermined the country's slow progress toward democracy and raised fears of Iraq-style attacks."It will take many, many more years before we can defend ourselves with our own means, before we can feed ourselves or work for our development with our own means," Karzai said.