An investigation is underway after a doctor riding his bicycle on an Orange County highway was hit by a Lexus and then injured by the driver, who was then restrained by shocked bystanders.

Southern California authorities say the bicyclist, later identified as 58-year-old Michael Mammon, died after being struck from behind by a white Lexus while driving on Pacific Coast Highway in the Dana Point area.

After the accident, the driver of the Lexus got out of the car and attacked Mamon with a knife.

Witnesses say the suspect punched the bicyclist and stabbed him at least once in the back.

Mamone died after being rear-ended by a white Lexus while driving on Pacific Coast Highway in the Dana Point area

Around 3 p.m., the Orange County Fire Department responded to a call that a bicyclist had been hit by a vehicle near Crown Valley Parkway and East Pacific Coast Highway.

The suspect, later identified by authorities as Vanroy Evan Smith, 39, of Long Beach, was detained by bystanders and later taken into custody on suspicion of murder.

A knife believed to have been used in the attack was found at the scene. The sheriff’s office has not yet said if a gun was also recovered.

Officials said there is no connection between the victim and the suspect.

Since 2011, Mamon has worked as an emergency physician at Providence Mission Hospital Laguna Beach.

The hospital said in a statement: “We are stunned by this devastating tragedy. The entire Mission Hospital family mourns the loss of an incredible physician and friend. We will honor Dr. Mamone’s dedication to our community and passion for medicine by continuing to provide exceptional care.”

Around 3 p.m., the Orange County Fire Department responded to a call that a bicyclist had been hit by a vehicle near Crown Valley Parkway and East Pacific Coast Highway.

A knife believed to have been used in the attack was found at the scene. Officials said there is no connection between the victim and the suspect

Mission staff said he was an “amazing doctor.”

Mammome often rode his bike to work as he lived a few blocks away.

He was killed less than a mile from the hospital.

“That’s the irony of this whole thing. If a patient was brought in in such a condition, he would do anything to save him. He saved so many lives here, and he died very close to where he saved hundreds of lives,” said cardiologist Dr. Don Atwal.

Orange County prosecutors said they are currently investigating about 70 car deaths, with quite a few related to road rage, which appears to have spiked since the lifting of Covid restrictions and the return of people to driving.

Other cyclists riding the same stretch of Pacific Coast Highway agreed that the drivers seemed less patient and angry, Fox L.A reports. They said the crash happened on a narrow stretch of Pacific Coast Highway with little room for bikes and cars, adding that quite a few people have stopped cycling in the area.

Anyone with information is asked to contact the Orange County Sheriff’s Department at 714-288-6740. You can remain anonymous by calling Orange County Crime Stoppers at 1-855-TIP-OCCS.