The incident occurred at the intersection of Euclid and Valencia at approximately 9:51 a.m.
Police said the suspect was driving a stolen SUV and hit a Honda with two people inside.
The passenger in the Honda was killed and the driver was transported with traumatic injuries, police said.
The driver of the SUV was taken into custody on suspicion of driving a stolen vehicle.
Witnesses said the suspect was speeding and driving erratically.
Police later said the suspect was believed to have been driving under the influence of drugs.
#Fullerton PD confirms driver of black SUV taken into custody on suspicion of driving a stolen car. Passenger inside Honda died on scene. Driver of Honda taken to hospital. Witnesses say driver of stolen car was speeding, driving erratically. @ABC7 pic.twitter.com/esMlYgafiA— Greg Lee (@abc7greg) April 1, 2019