According to the CHP, a Toyota Prius and a semi-truck were involved in the accident on I-605 S and Lower Azusa Road

Baldwin Park, Calif. – One person was injured in a collision that took place in Baldwin Park early Tuesday morning, according to the California Highway Patrol.
The collision took place on I-605 S at the Lower Azusa Road offramp at about 12:19 a.m.
According to the CHP, a Toyota Prius and a semi-truck were involved.
One person had major head injuries.
Lanes were blocked as crews worked to clear the scene.
The cause of the collision is under investigation.