Two people were killed and several more injured after a wrong-way driver caused a multiple-car collision early Sunday on the 134 Freeway in Pasadena, according to local authorities.

The California Highway Patrol received a call at 8:12 a.m. of a traffic collision on the westbound freeway at North San Rafael Avenue, and arrived around 8:30. Pasadena city spokesperson Lisa Derderian said local police responded within minutes.

The cause is still being investigated by CHP, but Derderian said preliminary reports say that a wrong-way driver caused the crash. CHP logs note that a vehicle was driving eastbound in the westbound lane.

Derderian confirmed one person was killed at the scene, and another person died after being transported by ambulance. Three more people have “significant injuries,” with another reporting “minor complaints.”

Several fire trucks and engines and ambulances quickly arrived, she said.

“First responders respond to accidents every day, but stated this is one of the most horrific crashes they’ve seen in a long time, with the impact and injuries involved,” Derderian said.

Derderian said an emergency helicopter was flying overhead “very low” shortly after the crash “as a precaution, to look for any additional victims that could have been ejected from vehicles.” There have been no reports so far of more bodies.

Traffic was being diverted on all westbound lanes beginning at Fair Oaks Avenue, CHP said.

The freeway was expected to open in the hours after the crash, but authorities expected side streets where traffic was diverted could be affected for longer.