The U.S. military says three American troops and an Afghan soldier were wounded in a roadside bomb blast early Wednesday in southeastern Afghanistan.

The military says the attack on their convoy occurred near Qalat, the capital of Zabul province.

A military statement says one U.S. soldier suffered shrapnel wounds, while another had a possible concussion when the blast went off near their armored vehicle. Both are in stable condition. The third American and the Afghan soldier were treated at the scene.

Remnants of Afghanistan's ousted Taleban militia and other Islamic militants frequently attack U.S. military and Afghan government targets in the region, where thousands of American soldiers are hunting al-Qaida and Taleban fighters.