San Diego Police say the man had been drinking when he crossed El Cajon Blvd. on Saturday night.

SAN DIEGO — A suspected drunken pedestrian suffered serious injuries when he illegally crossed a street in the University Heights community of San Diego and was struck by a vehicle, authorities said Sunday.

The 36-year-old man suffered an open fracture to his leg and a partial amputation of his foot, the San Diego Police Department reported.

Police said the man was illegally crossing in the 2300 block of El Cajon Boulevard — walking from the north sidewalk to the south — and was struck about 9:15 p.m. Saturday by a 2007 Mercedes-Benz S550 that was traveling in the No. 1 lane of westbound El Cajon Boulevard.

The motorist who was driving the Mercedes-Benz was not suspected of having been driving under the influence of alcohol. However, the pedestrian was determined to have been drinking.

The SDPD Traffic Division will be handling the investigation.