SAN DIEGO — Authorities say a crash that left 13 people hurt in rural East County Tuesday was the result of a high-speed chase between U.S. Border Patrol and a driver who crammed a dozen people into the bed of their pickup truck.

Authorities released new details on the pursuit Wednesday after sparse information was initially released on the crash, which happened on Interstate 8 near the Pine Valley community east of Alpine.

The chase started shortly after 6 p.m. when USBP agents tried to pull over a Chevrolet Silverado and the driver refused to stop, according to California Highway Patrol. The truck “fled at a high rate of speed,” CHP said, and agents followed.

The driver eventually appeared to be exiting the freeway at Buckman Springs Road. Instead, the driver “turned abruptly to the left, back into the main travel lanes,” CHP said. The driver lost control of the Chevy, swerving across the lanes and onto a dirt median, where it rolled over.

Agents discovered that there were 13 adults traveling in the Silverado, with only the driver in the cab and the rest of the people in the truck bed. No one aside from the driver was in a seatbelt, according to CHP, and the other 12 people were thrown from the truck onto the side of the highway.

They suffered “moderate to major injuries” and were taken to various hospitals, officials said, but there was no update on their status Wednesday. The driver was taken into custody by border officials.

Details on what charges the driver could face were not immediately available, though officials added that alcohol or drugs were not believed to be a factor in the crash.