Authorities are trying to subdue an armed elderly woman who has barricaded herself at a Southern California mobile home park for most of the day and shot at a police robot.

Los Angeles County sheriff's officials say they were called around dawn Thursday by a woman saying she needed medical assistance.

When deputies and firefighters arrived at the mobile home park in Topanga Canyon, near Malibu, the woman waved a gun at them. They took cover and evacuated the park.

Sheriff's officials have been working to resolve the situation all day, but the woman remains holed up after more than 12 hours.

KABC-TV reports authorities have tried tear gas and a crisis-negotiation robot. The station says the woman fired a gun at the robot, hit it with a broom and threw a cover over it.