A vehicle broke free from a tow truck on Interstate Highway 580 in Castro Valley and onto the BART tracks on Tuesday, blocking highway traffic and BART service on the Blue Line between the Castro Valley and Dublin/Pleasanton stations.

BART alerted about the obstruction on the tracks just after 3 p.m. The California Highway Patrol said a black Hyundai coupe was on a flatbed tow truck heading west on Highway 580 when it fell off and led to a crash with two other vehicles and involving "major injuries." 

The CHP said all lanes of westbound Highway 580 were blocked at the location above Five Canyons Parkway, just south of E. Castro Valley Boulevard. The number 1 lane of eastbound 580 was also blocked. 

The Hyundai was lodged in the westbound trackway, and there was visible damage to the track and the electric third rail. The vehicle managed to fly across an approximate 20-foot gap between the elevated highway and BART tracks, which are about 25 to 30 feet above the ground.

It was unclear how many people were injured, the CHP said.

An Alameda County Fire Department spokesperson said the crash sparked a brush fire that has since been extinguished.

This is a breaking news update. More information to be added as available.