A May Day march turned into an "occupation" when several dozen Black Bloc anarchists broke into an abandoned school then closed the gate behind them. Police sealed off Mission Street between 15th and 16th streets. After a few hundred Black Bloc anarchists marched around different parts of the city to commemorate May Day, a.k.a. International Workers' Day, some of them broke into an abandoned school near the intersection of 16th and Mission streets and occupied it. "This school is sitting empty, they're not using it while we have so many homeless people on the streets. Why doesn't the city let the homeless stay here?" said one anarchists, who refused to give his name. San Francisco police, who'd been tracking the march from the beginning, responded by closing off Mission Street between 15th and 16th streets, then clearing the sidewalks of both bystanders and anarchists. The anarchists locked the gates behind them. They'd come with various items that clearly showed this was not a spur-of-the-moment action but instead had some amount of planning behind it. After a standoff and negotiations between them and the police that lasted about two hours, the anarchists either voluntarily removed themselves from the property or were arrested and forcibly removed. A police commander at the scene said 11 people were arrested.