A doctor in Southern California was killed after a motorist hit his bicycle and then stabbed him outside the vehicle, police said.
Dr Michael Mammone, 58, was riding his bicycle on the Pacific Coast Highway in Dana Point when he was reportedly hit from behind by a Lexus.
The incident occurred around 3pm, according to the Orange County Sheriff’s Department.
The driver of the Lexus, Vanroy Evan Smith, 39, allegedly exited his vehicle and stabbed the injured doctor, police said.
Mr Smith is from Long Beach, California.
Witnesses claim they saw the attacker stab the doctor in his back at least once before pulling out a gun and firing multiple shots, Fox Los Angeles reports. The man was quickly disarmed by a pair of bystanders and held until police could arrive to arrest him.
When police arrived on scene, they found Dr Mammone lying on the ground in an intersection suffering from "severe injuries”.
Mr Smith was arrested on suspicion of murder.
Investigators said there is no known connection between Mr Smith and Dr Mammone.
“As of right now we currently don’t truly understand the why … as far as motivation and any type of relationship,” Orange County Sheriff’s Sargent Mike Woodruff told local broadcaster KTLA. “Investigators are keeping all options open to check those boxes if you will, to make sure they don’t leave anything uncovered.”
The doctor practised emergency medicine at the Providence Mission Hospital Laguna Beach.
"We are stunned by this devastating tragedy," the hospital said in a statement to Fox News Digital. "The entire Mission Hospital family is grieving over the loss of an incredible physician and friend. We will honor Dr Mammone’s dedication to our community and passion for medicine by continuing to provide exceptional care."