Two factory bosses and two engineers were detained in Bangladesh on Saturday, three days after the collapse of a building where low-cost garments were made for Western brands. At least 352 people were killed in the collapse.

More survivors were pulled from the rubble Saturday, but police said that as many as 900 people were still missing.

The owner of the eight-story building was on the run. Police said several of his relatives were detained to compel him to turn himself in, and an alert was sent to airport and border authorities.

Officials said that Rana Plaza, on the outskirts of the capital, Dhaka, had been built on spongy ground without the correct permits and that workers were sent in Wednesday despite signs and warnings the previous day that it was structurally unsafe. More than 3,000 people, mostly young females, worked in the building.

Anger at the negligence — and at the general working conditions of Bangladesh’s 3.6 million garment workers — has sparked days of protests and clashes, with police on Saturday using tear gas, water cannons and rubber bullets to quell demonstrators who burned cars.

Two engineers involved in building the complex were arrested at their homes early Saturday, Dhaka district police Chief Habibur Rahman said. The owner and managing director of the largest of the five factories in the complex, New Wave Style, were handed over to police after surrendering to the country’s garment industry association during the night.

The factory, which listed as its customers many European and North American retailers, occupied upper floors of the building, which officials said had been added illegally.

“Everyone involved — including the designer, engineer and builders — will be arrested for putting up this defective building,” said Shamsul Huq, junior internal affairs minister.

An alliance of leftist parties that is part of the ruling coalition said it would call for a national strike Thursday if all those responsible were not arrested by Sunday.

Rahman identified the owner of the building as Mohammed Sohel Rana, a leader of the ruling Awami League’s youth front.

“People are asking for his head, which is quite natural,” said H.T. Imam, an adviser to the prime minister.

Wednesday’s collapse was the third major industrial incident in five months in Bangladesh, the second-largest exporter of garments in the world after China. In November, a fire at the Tazreen Fashions factory in Dhaka killed 112 people.

Such incidents have raised questions about worker safety and low wages that could taint the reputation of the poor South Asian country, whose garment industry provides 80 percent — or $19 billion worth — of its exports. Sixty percent of the clothes go to Europe, 23 percent to the United States and 5 percent to Canada.

The Bangladesh Garment Manufacturers and Exporters Association asked garment-factory owners Saturday to produce building designs by July in a bid to improve safety.

Rescuers armed with rod cutters and drills pulled more than two dozen survivors from the precarious mound of rubble Saturday.

Marina Begum, 22, spoke from a hospital bed after her rescue Saturday.

“It felt like I was in hell,” she told reporters. “It was so hot, I could hardly breathe. There was no food and water. When I regained my senses, I found myself in this hospital bed.”

Frantic efforts were underway to save 15 trapped people who were being supplied with dried food, bottled water and oxygen.

Heavy machinery will not be used to remove bodies and debris until all the survivors are rescued, said Jahangir Kabir Nanak, junior minister for local government.

About 2,500 people have been rescued from the remains of the building in the commercial suburb of Savar, about 20 miles from Dhaka.

— Reuters