A car crash on the Diagonal Highway killed two people and injured two others late Monday, the Boulder Police Department announced.

A BMW sedan was going west on the highway about 11:20 p.m. when it turned south at 34th Street, in front of a Nissan Altima, police said. The BMW was hit by the Nissan, which was going down 34th Street.

Two passengers in the BMW died at the scene, police said. The passengers were a 53-year-old man and a 56-year-old man. Their identities will be released by the Boulder County Coroner’s Office after their families have been notified.

Both drivers were also injured. The driver of the BMW, a 79-year-old man, suffered critical injuries and the driver of the Nissan, a 21-year-old man, suffered nonlife-threatening injuries, police said.

Both drivers were hospitalized Tuesday morning.

Police were investigating the cause of the crash.

Anyone who witnessed the crash or has information about what happened is asked to call the police department’s traffic office at 303-419-9943.

The Diagonal Highway was closed in both directions for nearly seven hours as officers processed the scene. It reopened just after 6 a.m. Tuesday.