CONTRA COSTA (BCN) — Two separate crashes on the same stretch of Interstate Highway 80 in Contra Costa County early this morning resulted in a fatality and numerous injuries, according to the California Highway Patrol.

There were seven people injured in the two crashes, which both occurred on eastbound Highway 80 in Crockett where Caltrans work was being done overnight, CHP Officer Brandon Correia said.

The first occurred at 1:35 a.m. near the Cummings Skyway on-ramp as a sedan slowed down nearly to a stop as lanes tapered off for the highway construction work, Correia said.

An ambulance traveling behind the sedan failed to adjust its speed accordingly and collided with the back of the sedan, Correia said.

All three occupants of the ambulance suffered major injuries while the sole occupant of the sedan suffered minor injuries.

The Winters woman driving the ambulance was taken to Kaiser Permanente Medical Center in Vallejo and the two passengers, an Alameda man and a San Francisco woman, were taken to John Muir Medical Center in Walnut Creek.

They were all in stable condition this morning, Correia said.

The crash was followed by another collision in precisely the same area about two hours later.

At 3:24 a.m., a big-rig and a Mazda sedan collided on the highway for reasons that have not yet been determined, Correia said.

The vehicles were pushed toward the center divider and careened back into traffic after crashing into it. Three more vehicles then became involved in the crash, Correia said.

The driver of the sedan, a Davis man whose name has not yet been released, was pronounced dead at the scene, Correia said.

Each of the three vehicles that became involved in the chain-reaction crash had occupants who suffered minor injuries. The big-rig driver also suffered injuries considered minor.

Everyone involved in the crash remained at the scene, Correia said.

Both of the incidents are still being investigated, but Correia said preliminary information indicates that drugs or alcohol are not considered factors in the crashes.

The crash prompted the closure of lanes on the highway, but all lanes reopened by shortly after 6:30 a.m.