Eleven people were injured and a dozen vehicles damaged when a construction scaffold collapsed at the busiest crossing on the U.S.-Mexico border, located in San Ysidro, California.

A portion of the scaffolding put up to protect traffic from overhead construction work fell on top of 15 vehicles, San Diego fire department spokesman Maurice Luque said.

One of those hurt, a construction worker, was listed in serious condition, while the others suffered minor injuries, Luque said.

The accident forced the temporary closing of all 24 northbound lanes at San Ysidro and travelers were diverted to another crossing about 8 kilometers (5 miles) east. Southbound traffic was unaffected.

More than half of the northbound lanes were open again Thursday.

The San Ysidro crossing handles around 50,000 northbound vehicles and 25,000 pedestrians every day.