A big rig, which overturned on Interstate 5 in Carlsbad, injuring two people, blocking freeway lanes and spilling diesel fuel, turned the Wednesday morning commute into a real nightmare for some North County motorists, authorities said.

A SigAlert was issued when the CHP shut down three of the freeway’s four lanes. As of 9:45 a.m., all but one of the lanes was reopened to traffic, according to the CHP.

The crash occurred on the southbound side of the freeway, just north of Tamarack Avenue, around 7:15 a.m., according to the California Highway Patrol.

Paramedics took the two injured victims to the hospital, said a dispatcher for the Carlsbad Fire Department.

Traffic was also backed up to El Camino Real for a time on westbound Highway 78, which feeds into I-5, the CHP reported.

A county Hazmat team was called to clean up about 15 gallons of diesel fuel spilled from the big rig, the CHP reported.

By 9:45 a.m., all but one of the lanes was reopened, and the fourth was back in service by shortly before 10:30 a.m, according to the CHP.