Five people have been taken into custody in connection with the collapse of a poorly-constructed building in Bangladesh that killed at least 348 people, as the search for survivors continued.

Rescuers were able to save 29 people from the collapsed-building on Saturday, but as the day wore on, they said the voices of the survivors were growing weaker after four days of being trapped amid the rubble.

Most of the victims were crushed by sections of the eight-storey structure which collapsed Wednesday morning. According to officials, the top three floors of the building were illegally constructed.

The tragedy hit Bangladesh’s large garment industry and brought attention to the poor working conditions of factory workers, who work for around $38 a month to produce clothing for top international brands.

Since the collapse, violent public protests have continued on the streets of the capital, Dhaka, and have spread to Chittagong, a southeastern city.

Two owners of the garment factory were among those arrested on Saturday. A Dhaka court ruled the owners can be questioned by police for 12 days without any charges being filed. Two government engineers and the wife of the building owner, who is now on the run, were also arrested.

Authorities are still searching for Mohammed Sohel Rana, a local politician and owner of the collapsed Rana Plaza building, who hasn’t been seen in public since the building collapsed. Negligence cases have been filed against him.

On Saturday, rescuers were finally able to reach the ground floor of the building, after drilling 25 holes from the top of the rubble, Brig. Gen. Ali Ahmed Khan, head of fire services, said.

"We are still getting response from survivors though they are becoming weaker slowly," he said.

"The building is very vulnerable. Any time the floors could collapse. We are performing an impossible task, but we are glad that we are able to rescue so many survivors."

Khan said the operations will continue overnight, as chances of people surviving for a fifth day with possibly serious injuries are fading.

Rescuers, police, soldiers and medical staff worked non-stop Saturday in an attempt to reach the survivors. Bottles of water and cylinders of oxygen were passed down a human chain to survivors still trapped in the structure.

Dead bodies pulled from the ruins were taken to a nearby high school that had been turned into a morgue. Many people gathered around the school waving photos of their missing family members and waiting for news.

Junior local government minister Jahangir Kabir Nank set the death toll at 348. A spokesperson for the military said that 2,429 survivors were accounted for, including the 29 who were rescued on Saturday.

A garment manufacturers’ group said the factories inside the Rana Plaza employed around 3,122 workers, but it is not clear how many were inside at the time of the collapse.

Police said they ordered an evacuation of the building on Tuesday after cracks were reported, but the factories ignored the order. After the building collapsed officials said numerous construction regulations had been violated.

The building collapse is the worst disaster to hit the country’s garment industry.

Five months ago a factory fire killed 112 people and prompted widespread promises to improve safety standards. However very little has changed in Bangladesh, which continues to attract some of the world’s top brands – including Britan’s Primark and Canada’s Joe Fresh -- due to low wages for workers.

Representatives from Loblaw Inc. -- parent company of Joe Fresh – said on Friday that it was sending company officials to Bangladesh to probe the cause of the collapse.

“We will be looking at what are the efforts that have been made and what else needs to be done. Where do we need to put pressure? We will also be discussing these issues with the federal government," Diane Brisebois of Loblaw Inc., said.

Mark Lalonde, Director of CKR Global Risk Solution, told CTV News Channel on Saturday that companies that hire overseas factories to produce their products face multiple challenges when it comes to enforcing safety standards, including having to ensure compliance with no full time staff on the ground.

He also noted that companies face additional challenges because some overseas factories put on a “show” to demonstrate that safety standards are being met, but then sub out the work to sweatshops once company representatives have left the country.

Lalonde said it is unlikely that companies will move their production out of developing countries in the wake of the Bangladesh building collapse.

“Competition will remain the same for the lowest possible production,” he said. “It’s up to the consumer to check where their goods are coming from that they’re buying and to ask questions and be informed.”

With files from The Associated Press