AN ARMED man has taken three people hostage at one of the largest veterans homes in California, United States.

The incident at the Yountville Veterans Home is currently classified as an “active shooter situation”. The facility is in lockdown.

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.

Authorities said they could not immediately say if anyone was injured.

“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 at 10.20am local time.

Police received reports of an “active shooter” and within four minutes had an officer on the scene. Gunfire was exchanged between the officer and the gunman.

The three hostages are being detained in “one room”, officials said in a statement. There are hostage negotiators at the scene but they are yet to make contact with the suspect.

Fransen said authorities were working to establish a secure perimeter around the facility.

An armoured police vehicle, ambulances and several fire trucks were at the scene.

Some 15-30 shots have been fired, according to reports.

California Highway Patrol have said they have officers on the scene and are attempting to “bring the situation to a safe conclusion”.

In a press confence, authorities stated that they have not yet had any contact with the gunman.

The hostages are employees, not residents, according to officials.

“We are approaching this as an active shooter situation. There have been shots fired, exchanged with out deputies,” Sheriff John Robinson Napa County Sheriff’s office said.

“I don’t know at this time the status of the hostages,” he said, when asked if they had been injured.

They said they know who the gunman is, but could not provide more details at this stage.

The gunman released some hostages and kept three, according to the Sheriff Robinson.

According to CNN, the veterans home is the largest in the country and is home to some 1000 elderly and disable residents. It is located in Yountville, north of San Francisco.

The state Veterans Affairs department says the home that opened in 1984, and offers residential accommodations with recreational, social, and therapeutic activities for independent living.

A neighbouring school was also initally placed in lockdown as well, however the lockdown has now been lifted.

A SWAT team is also on the way to the scene.

There are no reported injuries at this stage.

Events manager Elizabeth Naylor, who was working about 16km 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 warning them to avoid the area.

More to come ...