Officers responded to a report of a shooting at Pa's Mexican and Filipino Cuisine restaurant located at 916 B St. at about 1:15 a.m., San Rafael police Lt. Dan Fink said.
When officers arrived, they found a 31-year-old man who had been shot multiple times, Fink said.
He was taken to Marin General Hospital where he underwent emergency surgery and is in very critical condition, police said.
Fink said a Hispanic man wearing a dark hooded sweatshirt walked into the restaurant, walked up to the person, shot him several times and ran out.
It is unknown if the suspect and victim know each other.
There were about 20 other people in the restaurant at the time of the shooting but no other injuries were reported, according to Fink.
Police said "an intensive investigation" into the shooting is underway.
Anyone who was at Pa's restaurant at the time of the shooting who has not yet spoken to police or anyone else with information about this case is asked to call San Rafael police immediately at (415) 485-3000.