FREMONT, Calif. — After a quarter-century of production, the last car rolled off the assembly line at the New United Motor Manufacturing Inc. plant in Fremont April 1 and workers headed home to uncertain futures.

“It’s a very sad day for Fremont,” Mayor Bob Wasserman said.

Sergio Santos, president of United Auto Workers Local 2244, which represented 4,700 employees at the auto plant, called April 1 “an emotional day for everyone.”

NUMMI officials said the last car produced at the plant, a red S-grade Corolla, came off the assembly line at 9:21 a.m.

“To see the last car come off the line was very emotional,” Santos said, adding the plant’s closure “will rip up some families” because they will now have a hard time paying their mortgages and bills.

NUMMI, which began operations in 1984, was a joint venture between General Motors and Toyota. GM announced last June that it would withdraw from the partnership, and Toyota announced in August that it wouldn’t order any more vehicles from the plant after April 1.

“There was a long and harmonious relationship with NUMMI and Toyota, and it’s very said to see them leave,” Wasserman said.

NUMMI president and chief executive Kent Ogura issued a statement lauding employees for their accomplishments.

“We want to thank generations of NUMMI team members whose skill and pride in their work contributed to numerous innovations in automotive assembly here in Fremont,” Ogura said. “We also want to thank Toyota for helping to retain NUMMI workers and ensure efficient production until the last day of operations at this plant.”

He continued, “Our attention now will focus on helping to find a new owner that will re-use this site so that it continues to serve the Fremont community and the Bay Area.”

NUMMI officials said some employees will stay at the 370-acre facility over the next few months to help sell assets, perform remediation and provide security.

Alameda County Supervisor Keith Carson and other local leaders have talked to business groups from China about using the facility to make cars or other products but nothing has come of those talks so far.

Carson, who is president of the East Bay Economic Development Alliance, said April 1 that the quickest re-use for the site would be to have another carmaker to take it over.

He said it would take longer for other uses for the facility because there probably would need to be a lengthy process to clean up the site and decide who would pay for those costs.

Wasserman said the Fremont City Council has applied for a $385,000 federal grant to study how to re-use the facility as well as adjacent land that he said is either vacant or under-utilized. He said the city hasn’t received the grant yet but that he’s “very confident we will get it.”

Wasserman said the site is attractive because it’s near two major freeways and a future BART station, and he thinks that “if there were a booming economy, developers would be standing in line.” The mayor said he’s not certain if having another carmaker take over the site would be the best long-term solution for Fremont.

“Despite their recent problems with recalls, Toyota is the most successful automaker ever and if they can’t make that site profitable, who can?” he said.

Wasserman said there’s been talk of having a maker of alternative energy cars, such as Tesla Motors, use the plant, but he said at this point there isn’t enough demand for such cars to make such an idea feasible.

“Tesla wouldn’t even occupy one-fifth of the plant,” he said.

Wasserman said one possibility would be to have the site used for a combination of retail space, office space and housing. Wasserman said the NUMMI site and surrounding area would also “absolutely” be a good site for a baseball stadium.