Two homicide car bombers killed at least seven Iraqi customs officials Sunday along the Syrian border, the U.S. military said, forcing the temporary closure of the checkpoint.

The explosions occurred around 2:20 p.m. at the Walid (search) border crossing point, said Marine Capt. Jeffrey Pool, a spokesman for U.S. troops in the western region of Anbar (search). He did not provide further details.

The porous Syrian border is considered the main entryway into Iraq for foreign fighters.

U.S. troops closed the border checkpoint on the Iraqi side after the blasts and authorities turned back 300 Iraqis trying to enter from Syria (search), according to a Syrian source who requested anonymity because of the sensitivity of the issue.

There are three legal border-crossing points between Syria and Iraq. The checkpoint at the frontier town of Qaim (search), however, has been closed for about a year for security reasons.