A gunman took at least three people hostage at the largest veterans home in the United States on Friday, leading to a lockdown of the sprawling grounds in California, authorities said.

Authorities said they could not immediately say if anyone was injured. Police evacuated the property of the Veterans Home of California after reports of a man with a gun at the facility in the small town of Yountville in Napa Valley, the heart of Northern California wine country.

"We do have an active shooter situation with a hostage situation in Yountville," California Highway Patrol Officer John Fransen told San Francisco Bay Area news station KTVU-TV.

The Napa Valley Register reported that a man wearing body armor and armed with an automatic weapon entered the home.

Fransen said authorities were working to establish a secure perimeter around the facility, which is home to about 1,000 residents. An armored police vehicle, ambulances and several fire trucks were at the scene.

Events manager Elizabeth Naylor, who was working about 10 miles north of the veterans' home, said she heard waves of emergency sirens. She said she's lived in Yountville since 1995 and is rattled about a shooting so close to home.

"I don't know the world we live in today, I really don't," she said. "This is a little community and we all know each other. Napa Valley is a wonderful, beautiful place and to know this is in your background, it's unsettling."

The Napa County Sheriff's Department issued an alert to residents at 10:30 a.m. warning them to avoid the area. The department did not immediately respond to a telephone call from The Associated Press.

The state Veterans Affairs department says the home that opened in 1984 is the nation's largest veterans home, with about 1,000 elderly and disabled residents. Its website says it offers residential accommodations with recreational, social, and therapeutic activities for independent living.

The grounds also are home to a 1,200-seat theater, a 9-hole golf course, a baseball stadium, bowling lanes, a swimming pool, and a military Base Exchange branch store.