A 78-year-old man riding a bicycle was killed around noon Tuesday after a collision with a white SUV in San Marcos.

The crash happened on San Marcos Boulevard near Rancho Santa Fe Road, according to the San Diego Sherriff’s Department.

Watch Commander: Deputies from the San Marcos Sheriff’s Station are conducting a traffic collision investigation. The roadway is shut down on San Marcos Blvd. just west of Rancho Santa Fe Rd. Please avoid the area and use an alternative route until further notice. Thank you.…

— San Diego Sheriff (@SDSheriff) April 21, 2026

It is unknown what led up to the deadly crash. The driver of the vehicle remained at the scene, according to deputies.

All roads near the collision were reopened just before 5 p.m. by the Sheriff’s department.