Cape Town, South Africa — Rescue teams searching for dozens of construction workers missing after an apartment complex collapsed in South Africa brought out more survivors Tuesday as they entered a second night of desperate work to find anyone alive in the wreckage. At least seven people have been confirmed dead.

Authorities said 26 workers had been rescued from the site where the five-story building collapsed Monday while under construction in George, about 250 miles east of Cape Town on South Africa’s south coast. An additional 42 people were still believed to be buried in the debris of concrete and metal scaffolding.

Rescuers were hopeful of more people being found alive after saying earlier that they had made contact with at least 11 workers trapped in the rubble and were communicating with them.

It wasn’t immediately clear how many of those had been rescued, but five survivors were brought out on Tuesday, adding to the 21 found on Monday, according to a count provided by city authorities. There were 75 construction workers on the site when the building collapsed.

Rescuers erupted in applause as one of the survivors was brought to the surface. They yelled at the man to “stay with us!” as he was pulled out of a gap in the wreckage and put on a stretcher. They then shouted to him, “you are outside now!”

Authorities haven’t given updated details on the extent of the injuries but said in the first few hours after the collapse that at least 11 of the workers rescued had severe injuries.

Colin Deiner, head of the provincial Western Cape disaster management services, said the search-and-rescue operation would likely take at least three days. He said it would take at least the rest of Tuesday to bring out all 11 of the survivors they had located, which included a group of four workers trapped in what was the basement of the building.

Some of those workers had limbs under concrete slabs and couldn’t move, Deiner said.

“We are going to give it the absolute maximum time to see how many people we can rescue,” Deiner said at a news conference. “It is very, very difficult if you are working with concrete breakers and drillers close to people.”

“Our big concern is entrapment for many hours, when a person’s body parts are compressed. So, you need to get medical help to them. We got our medics in as soon as we possibly could.”

Deiner said it was possible that there were more survivors deeper in the wreckage and a process of removing layers of concrete would begin in time.

More than 100 emergency services and other personnel had been working on the site in shifts. Rescuers were using sniffer dogs to try to locate workers. Large cranes and other heavy lifting equipment was brought in to help and tall spotlights were erected to allow the rescuers to work in the dark.

Deiner said a critical part of the rescue operation came when they had ordered everyone to remain quiet and shut off machinery so they could listen for any survivors. That’s when they located some of them, he said.

“We were actually hearing people through the rubble,” Deiner said.

Several local hospitals were making space in their trauma units in anticipation that more people might be brought out alive. More than 50 emergency responders had also been brought in from other towns and cities to help, including a specialized team that deals with rescue operations in collapsed structures.

Family and friends of the workers had gathered at the nearby municipal offices and were being supported by social workers, the George municipality said.

Authorities were starting investigations into what caused the tragedy and a criminal case was opened by police, but there was no immediate information on why the building collapsed. CCTV footage from a nearby home showed the concrete structure and metal scaffolding suddenly collapsing, causing a plume of dust to rise over the neighborhood.

People came streaming out of other buildings after the collapse, with some of them screaming and shouting.

Alan Winde, the premier of the Western Cape province, said there would be investigations by both the provincial government and the police.

Authorities said that under city law the private construction company’s engineers were responsible for the safety of the building site until its completion, when it would be handed over to the city to check and clear.

Winde said the priority was the rescue effort and investigations would unfold after that.

“At the moment, officials are focused on saving lives. This is our top priority at this stage,” Winde said.

The national government was being briefed on the rescue operation, Winde said. South African President Cyril Ramaphosa released a statement offering his condolences to families of the victims and also called for investigations into the cause of the collapse.