WASHINGTON (AP) — Newly revealed testimony from top military commanders involved in the U.S. response to the Benghazi attacks suggests that the perpetrators of a second, dawn attack on a CIA complex probably were different from those who penetrated the U.S. diplomatic mission the evening before and set it ablaze, killing Ambassador Chris Stevens and another American.

The second attack, which killed two security contractors, showed clear military training, retired Gen. Carter Ham told Congress in closed-door testimony released late Wednesday. The assault probably was the work of a new team of militants, seizing on reports of violence at the diplomatic mission the night before and hitting the Americans while they were most vulnerable.