SAN DIEGO, CA – A motorcyclist and bicyclist both suffered serious, life-threatening injuries Thursday morning when they collided in a Mira Mesa intersection, police said.

The crash on Mira Mesa Boulevard at Parkdale Avenue shut down a two- block stretch of Mira Mesa Boulevard for about an hour after the 5:37 a.m. crash, San Diego police officer Tony Martinez said. The eastbound lanes of the thoroughfare were reopened a little before 7 a.m., but the westbound lanes remained closed for several hours.

A 28-year-old man was riding his bicycle on the south side of Mira Mesa Boulevard when he attempted to cross the street at Parkdale Avenue against a red light, Martinez said. A 56-year-old man on a motorcycle riding in a middle lane struck the bicyclist as he entered the intersection.