U.S. officials say scaffolding collapsed on several cars at a busy border crossing with Mexico, forcing vehicle traffic to be detoured to nearby border crossings.

U.S. Customs and Border Protection reopened the San Ysidro crossing to pedestrian traffic late Wednesday, hours after the collapse.

The scaffolding collapse injured several people. Eleven people, including four construction workers and a pregnant woman, were hospitalized.

CBP officials say they do not have a timetable for when northbound lanes into the United States at San Ysidro will reopen to vehicles. Southbound lanes into Mexico remain open.

The San Ysidro entry port is undergoing a nearly $600 million renovation.