A van carrying suspected illegal immigrants crashed near the border with Mexico on Friday as it was being chased by the Border Patrol, injuring more than 20 people, eight critically.
Twenty-eight people were in the van when it overturned while trying to avoid a strip of spikes that agents had placed in its path.
Eight people suffered life-threatening injuries. Another 13 were being treated for minor injuries, said Maurice Luque, a spokesman for the San Diego Fire-Rescue Department.
The chase began when Border Patrol agents received reports that large numbers of illegal immigrants were being loaded into three vans in the Otay Mesa industrial district of San Diego.
Agents stopped two of the vans, taking about 60 suspected illegal immigrants into custody, Border Patrol spokesman Richard Kite said.
A third van tumbled down an embankment, littering the roadway with water bottles, clothing and debris.
The vans were loaded near a warehouse where investigators last month discovered the exit to a 2,400-foot tunnel used to smuggle drugs, the longest passageway ever found under the U.S.-Mexico border.