SAN DIEGO — A traffic collision has blocked the right four lanes on southbound Interstate 5 at State Route 163, Caltrans said in a tweet at 2:34 p.m. Friday afternoon.

According to a traffic alert, an overturned vehicle has halted traffic. Congestion is reported to be backed up all the way to Old Town.

Motorists in the area should expect delays.

SKYFOX is headed to the scene.

This is a developing story. Please check back for updates.