Janitors cleaning Twitter's HQ went on strike over unfair labor practice, SEIU Local 87 says.
Twitter ended the contract with the firm employing the janitors, per the California Labor Federation (CLF).
The janitors face losing their jobs on Friday when the contract with the janitorial company is set to end.
Janitors at Twitter's headquarters went on strike on Monday after Elon Musk's company failed to negotiate a new contract with Flagship, the janitorial company that employs them, according to unions.
The strike, which started at 6 a.m., was over unfair labor practice, according to the Service Employees International Union (SEIU) Local 87, which said it represents 5,000 janitors in the San Francisco area.
The union shared a picture of people who appeared to be demonstrating outside Twitter's headquarters in San Francisco. Some held up boards that read "justice for janitors" and "respect workers' seniority."
Twitter has ended the contract with the company that employs the janitors, the California Labor Federation (CLF), an organization made up of more than 1,200 unions, said in a Twitter thread. The CLF said Twitter had indicated its new contractor would not rehire the janitors.
According to the CLF, the last day of the contract is December 9. It wasn't clear which janitorial company Twitter has picked as its new contractor.
Employment law in San Francisco states that new contractors for janitorial services have to hire the workers from the terminated contractor for 90 days while a company transitions from the old contractor to the new contractor.
If the workers are not hired, they can receive compensation and benefits in return, per law.
Janitors told NBC News Bay Area they had been locked out of the building since Friday without prior warning.
In a video, Olga Miranda, the president of the SEIU Local 87, said the janitors working at Twitter's headquarters were told less than three weeks before Christmas they were going to lose their jobs and described the move as "unexpected." The clip was tweeted by Sergio Quintana, an NBC News Bay Area reporter.
"Twitter doesn't seem to understand how important it is to keep a clean house and respect the people who take out the trash," the CLF wrote in a tweet, adding the hashtag #TakeOnTheTwit.
Twitter and Flagship didn't immediately respond to Insider's request for comment.