A motorcycle laden with explosives detonated Sunday at a market in Helmand Province, killing five people - including four children - and injuring eight others, NATO's International Security Assistance Force said Saturday.

An ISAF statement said a second explosive device discovered on a donkey in the area was successfully defused. There was no way to independently verify the information.

U.S. Gen. David Petraeus, who assumed command of the Afghanistan mission on Sunday, accused insurgents of "killing and maiming innocent Afghan civilians on a daily basis."

"No tactic is beneath the insurgents; they repeatedly kill innocent civilians, and they frequently seek to create situations that will result in injury to Afghan citizens," Petraeus said in the statement.

Also Sunday, ISAF reported two members of the coalition military force died in separate incidents in southern Afghanistan.

One soldier was killed in a bomb explosion Sunday, and another died while on combat patrol on Thursday, according to an ISAF statement. No further details were available.