Separate bomb explosions in Afghanistan's volatile east and south killed eight American civilians, and four troops and a journalist from Canada today (Wednesday), according to U.S. and NATO officials.

AP reported a suicide attacker detonated explosives at Forward Operating Base Chapman in Khost province near the Afghan border with Pakistan, killing eight American civilians and wounding others, U.S. officials in Washington said.

An attacker wearing a suicide vest caused the explosion, according to a senior U.S. official in Washington. Another senior U.S. official in Washington said there were conflicting reports on the number of casualties, but that others were injured in the attack.

Meanwhile, in the south, NATO said that the four Canadian troops and a reporter embedded with their unit died when their armored vehicle hit a bomb while on an afternoon patrol south of Kandahar city.

The Canadian Press identified the journalist as Michelle Lang, a 34-year-old health reporter with the Calgary Herald, who was on her first assignment to Afghanistan.

The military has not disclosed the names of the troops because relatives had not all been notified.