Mexico's federal highway authority says the collapse occurred about 93 kilometres south of the border city of Tijuana. The road leads to the port city of Ensenada, on the Baja California peninsula.
The agency said yesterday the road was closed in the early morning hours, after the collapse was detected.
The agency said the collapse was caused by seven small earthquakes ranging in magnitude from 1.3 to 4.3.
It said the roadway runs over a known geological fault in the area, and that it had been raining heavily. No injuries were reported.