SAN DIEGO — A trucker hauling a large trailer of Amazon packages crashed on rainy Interstate 805 early Sunday morning, scattering boxes across the lanes and shutting down traffic for hours.

The crash happened in the University City area around 1 a.m., according to California Highway Patrol logs. It wasn’t immediately clear what caused the driver to lose control, but the big rig jackknifed, hit a bridge railing and flipped on its side. The trailer’s back door broke open and packages spilled onto the freeway, video from OnScene TV showed.

Callers told CHP that part of the truck then burst into flames, and dispatchers sent firefighters to check on the trucker and put out the fire. He appeared to avoid serious injury, as he stayed at the scene bundled in blankets and spoke with first responders rather than leaving in an ambulance, video showed.

All southbound lanes of I-805 were shut down near Governor Drive until about 8 a.m., according to CHP. At that point, officers allowed traffic to flow through the area in two lanes. The others remained closed past 1 p.m. Sunday as officials awaited a contractor to repair the broken railing.

The westbound ramp from state Route 52 to I-805 was also briefly closed. That had reopened to traffic by 8:30 a.m., according to Caltrans.