The manufacturers decided late Monday to close their factories because they had no other way to avoid the anarchy in the major industrial hub outside the capital, according to an official at the Bangladesh Garment Manufacturers and Exporters Association.

But the shut doors spurred more violence Tuesday, when workers smashed vehicles and set fire to at least five on a major highway, local police chief Sirajul Islam said. He said at least 30 people were injured after security officials used batons and tear gas to break up the demonstration.

“We are helpless,” Shafiul Islam Mohiuddin, a vice president of the industry group, said by phone. “We have decided to keep the factories closed for an indefinite period,” he said.

He said the garment factories were missing buyers’ deadlines because of the continuous unrest.

Over the last few days, thousands of workers took to the streets and attacked many factories in Ashulia. Hundreds have been injured in clashes with police, who are trying to remove them from streets and stop the violence.

The workers are demanding that the minimum wage rise to 5,000 takas ($73) a month. The current average monthly salary is 2,000 takas ($29) — that makes them the world’s most poorly paid garment workers.