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An active shooter with a rifle has taken three hostages at the nation's largest retirement home for veterans, authorities confirmed.

The gunman has targeted the Veterans Home of California in Yountville, less than 10 miles north of Napa. It’s the largest veterans home in the U.S., with about 1,000 aged or disabled veterans, according to the California Department of Veterans Affairs. The home is on lockdown.

Officers first responded to a call about shots fired, Chris Childs of the California Highway patrol told reporters at a press conference. There was an exchange of gunfire between his deputies and the suspect, who authorities believe has a rifle, though what kind or caliber wasn’t specified.

“There were many bullets fired,” John Robertson of the Napa Valley Sheriff’s office told reporters.

The California High Patrol, the Napa County Sheriff’s office, and the Federal Bureau of investigation are all at the scene. SWAT teams and crisis negotiators have been put to use.

The three hostages currently being held are Pathway Home employees, another veterans service organization, and that they do not work for the Yountville facility. Other hostages have already been released, Robertson said.

Authorities have not yet been able to contact the gunman, though they say they do know who he is and have tried to reach him on his cell phone.

Napa County Fire Captain Chase Beckman also told the Associated Press that the shooter has taken hostages. California Highway Patrol, which is responding to the situation, wouldn't comment on the number of hostages, but the retirement home told the local affiliate of ABC News that three people are being held.

Jan Thornton’s father, Harry Edwards, is a resident at the Yountville home. Thornton told VICE News that, after not being able to reach her father for awhile, she finally talked to him on the phone. Staff at the home had previously told her that he was safe and not in the same building as the shooter. The campus is large and made up of individual buildings.

“He’s a World War II veteran. He’s 96. He’s seen enough. He doesn’t need to see this,” Thornton said. “We were just hearing about all of this, and then here it comes to your doorstep.”

Video of the situation taken by Bay Area outlet KTVU reporter Mark Ibanez showed police and emergency vehicles outside the retirement home.

Around 2 p.m. local time, the retirement home posted a notice to its Facebook page regarding "reports of gunfire," and the Napa County Sheriff’s Department also posted that “police activity” was required at the veterans home.