Garment workers who sew clothes for Western brands clashed with Bangladeshi police Friday at a mass rally over the death of nearly 300 colleagues in a collapsed building as rescuers raced against time to find survivors.

Police fired tear-gas and rubber bullets at the angry crowds as the workers, some armed with bamboo sticks, blockaded roads and attacked factories in the textile hub of Gazipur outside the Bangladeshi capital Dhaka.

“The situation is very volatile. Hundreds of thousands of workers have joined the protests,” M. Asaduzzaman of Gazipur police control room told AFP.

Widespread anger has been fuelled by revelations that factory bosses forced the 3,000-strong work force to return to the building on Wednesday despite cracks appearing in the building the day before.