The protest over a Department of Homeland Security investigation that began in December and threatened the jobs of several immigrant workers at Tom Cat Bakery in Long Island City, Queens, was meant to begin at 6 a.m. on Friday.

But at 3 a.m., a few protesters arrived at the factory and chained themselves to the bakery’s trucks, disrupting morning deliveries. Four people were arrested, the police said.

By 7, more than 100 people had gathered in the rain, carrying signs that read “No Human Is Illegal” and “Rise and Resist.” Members of a marching band, the Rude Mechanical Orchestra, played as a group of 100 people marched back and forth along 10th Street, chanting in both Spanish and English.

Others in the food business around New York joined in the demonstrators’ call for “A Day Without Bread.” Eli and Max Sussman, brothers who run the Brooklyn restaurant Samesa, posted signs drawing attention to the protest, and to the rights of immigrant workers. On Friday, they donated 50 cents from the sale of every item that includes pita bread to a fund set up for workers. And at the register, they collected additional money.