San Francisco Bay Area health officials warned the public Tuesday to throw out any leftovers from a community Thanksgiving meal they suspect killed three people and sickened at least 14 people.

Officials are still trying to determine what specifically caused the illnesses, but they appear to have narrowed the source to a church-sponsored meal held at the American Legion hall in Antioch, California.

The free, community meal is an annual event that this year turned tragic. Thursday's feast hosted by the Golden Hills Community Church served 835 people, including residents of assisted living facilities, homeless people and anyone who wanted a holiday meal, health officials said.

All those who got sick ate food from the event and most became ill within 24 hours, said Dr. Louise McNitt, deputy health officer for Contra Costa County. The three people who died were admitted to the hospital on Friday and Saturday. More details about their deaths were not immediately available. As of Tuesday, one person remained hospitalized and the rest were recovering at home. Those who got sick ranged in age from teenagers to their 70s.

"Anyone with food from this event should not eat it, and should throw it away," McNitt told a news conference Tuesday. "This is likely a food-borne illness, but our investigation is ongoing."

The food came from a variety of sources. There were turkeys, hams and sweet potato dishes donated by volunteers who cooked them at home and other items that were prepared on-site, like instant mashed potatoes and stuffing, gravy and green beans that came from packages and were reheated, said Dr. Marilyn Underwood, environmental health director for Contra Costa Health Services.

Officials had initially said Monday that eight people got sick, including the three who died, and thought all those sickened lived at the same assisted living facility, leading to suspicion that they could have become sick from food eaten at home or elsewhere.

But by Tuesday, as the numbers increased, officials learned that the 17 people were residents from at least three assisted living facilities. Not all 17 attended the church meal; some were family members of people who worked at the facilities who ate leftovers brought home to them.

Some of them, including the three who died, lived at facilities called Minerva's Place and Minerva's Place IV in Antioch, the East Bay Times reported.

"It's tragic. They were thinking that they would have a good Thanksgiving, and now they have passed away," Emerito Gonzalez, an administrator at the residences was quoted as saying. "I just want to know what happened. I don't want this to ever happen again."

Autopsies were being performed Tuesday. Contra Costa County coroner's officials said they could not release the names of those who died pending notification of next of kin.