A Bangladesh court on Monday allowed police 15 days to interrogate the owner of a building that collapsed at Sawar in Dhaka last week and killed 382 people, even as rescuers used heavy machinery to cut through the destroyed structure after giving up hope of finding any more survivors.

Mohammed Sohel Rana, who was arrested on Sunday near the border with India, will be held for questioning on charges of negligence, illegal construction and forcing workers to join work. His father, Abdul Khaleque, was also arrested on suspicion of aiding Rana to force people to work in a dangerous building.

The illegally constructed 8-storey Rana Plaza collapsed in a heap on Wednesday morning along with thousands of workers in the five garment factories in the building. About 2,500 survivors have been accounted for.

Rana was brought to the Dhaka Metropolitan Magistrate’s Court in a bullet-proof vest, and led away to an unknown detention place after the magistrate granted a police request to hold him longer before filing formal charges. The crimes he is accused of carry a maximum punishment of seven years. More charges could be added later.

The collapse was the deadliest disaster to hit the garment industry in Bangladesh that is worth $20 billion annually and supplies global retailers.

In renewed anger against conditions in garment factories, a mainstay of Bangladesh’s economy, hundreds of workers poured into the streets in the Dhaka suburb of Ashulia and set fire to an ambulance on Monday, the Independent TV, a private network, reported. They also tried to set fire to a factory, it said. Authorities shut down all garment factories in Ashulia and Gazipur industrial suburbs, including one that had reportedly developed cracks and was evacuated earlier.

Volunteers, army personnel and firemen have worked round the clock since Wednesday, mostly using hands and light equipment to pull out survivors. Around midnight on Sunday, authorities deployed hydraulic cranes and heavy cutting machines to break up the massive slabs of concrete into manageable segments that could be lifted away.

“We are proceeding cautiously. If there is still a soul alive, we will try to rescue that person,” said army spokesman Shahinul Islam.

“There is little hope of finding anyone alive. Our men went inside and saw some dead bodies in the ground floor. But no one was seen alive,” said Brig. Gen. Ali Ahmed Khan, the chief of the fire brigade at the scene.

Gone are the civilian volunteers who had swarmed the site since the disaster. Only army soldiers in green camouflage and hard hats were visible, watching heavy machinery digging into thick concrete. Gone also are the waiting ambulances that over the past five days had rushed the rescued to hospitals.

Police have also arrested four owners of three factories. Also in detention for questioning are two municipal engineers who were involved in approving the building’s design. Local TV stations reported that the Bangladesh High Court has frozen the bank accounts of the owners of all five garment factories.