Water, possibly from a broken water main, flooded about a mile to a mile-and-a-half of northbound Interstate 805 at Interstate 15 this morning, authorities said.
The flooding was reported at 5:10 a.m., according to the California Highway Patrol.
The source was under investigation, though a broken water main was suspected, a CHP dispatcher said.
San Diego police advised commuters to avoid the area for several hours.
"It's dangerous,'' San Diego police Sgt. Kerry Tom said, adding that commuters "should get out of there as soon as possible. It's a complete mess.''