Sgt. Rob Schneider said the man was pronounced dead at a local hospital and Kathryn Graham, a spokeswoman for Marin General Hospital, confirmed the injured man had been taken there.
The Marin County coroner's office did not release the man's name but said an autopsy will probably be conducted Wednesday.
Police went to the residence at 49 Sunnyside Ave. around 11 a.m. to conduct a mental health evaluation and encountered an adult male armed with a knife, Schneider said.
The man became aggressive when officers tried to talk to him and police fired a Taser but could not stop the man from advancing toward the officers, Schneider said. One of the officers then shot the man, Schneider said.
Officers attempted life-saving measures until paramedics arrived and the man was taken to the hospital where he was pronounced dead, Schneider said. The Marin County Sheriff's Office is conducting an investigation of the shooting, Schneider said.
The incident happened across the street from the Wade Thomas Elementary School. The assisted living facility is operated by Buckelew Programs, said spokeswoman Dawn Stranne.
Steve Ramsland, executive director of Buckelew Programs, said three people were living at the facility on Sunnyside Avenue. He said some have jobs and are free to leave the facility but he would not comment on the status of the man who was shot today because of confidentiality rules.
"Our staff have been working closely with authorities and the community to investigate and to provide whatever support and assistance we can," Ramsland said.
"In more than 30 years of providing community based support services in the North Bay to nearly 1,000 people with mental illness a year, we have never had an incident like this occur. Something like this happening is very rare and is not likely to occur with most people who are getting help to manage their mental illness and are living productive lives.
"We would especially like to express our concern and sympathy for the family and friends of the person affected, as well as for the officers involved," Ramsland said.
Wade Thomas Elementary School Principal Chad Carvey said he had been told the man was aggressive and had threatened police with a knife.
He said police used Tasers to subdue the man but that "at some point police fired shots that struck the suspect" and he was taken to a hospital.
Carvey said all classrooms were locked and all students and staff stayed indoors. The school had students eat lunch inside, Carvey said.
After emergency vehicles left, students were allowed to play on the lower playground, Carvey said.
Elizabeth McGrady, executive director of the San Anselmo Preschool Center, located across Ross Avenue from Wade Thomas, said the elementary school contacted the preschool to warn them about the incident.
"The school called us and told us what happened and we kept the kids inside," McGrady said.
She said around 12:45 p.m. that she did not know the details of what happened and that the preschool was getting only "bits and pieces of information."