DHAKA, Bangladesh — Thousands of garment workers rampaged through industrial areas of the capital of Bangladesh on Friday, smashing vehicles with bamboo poles and setting fire to at least two factories in violent protests ignited by a deadly building collapse this week that killed at least 340 workers.

The protests, which continued into Saturday, came as rescue teams spent a third day searching for survivors in the rubble of the building, the Rana Plaza, in a suburb of the capital, Dhaka. Officials reported that 72 people were pulled out alive, a rare bit of good news in what is already considered the deadliest accident in the history of the garment industry — with a death toll expected to keep rising.

Prime Minister Sheikh Hasina ordered the arrests of the owner of Rana Plaza, as well as the owners of four garment factories that were operating on the upper floors of the eight-story building. Pressure also mounted on Western clothing brands that rely heavily on Bangladesh to manufacture their products; labor activists have found labels inside the wreckage for clothes being made for J. C. Penney, Cato Fashions, the British retailer Primark and other clothing brands.