Emergency crews in Miami continued to search for survivors on Friday after an oceanfront condominium partially collapsed a day prior.

Rescue efforts in the city, located in the southern US state of Florida, have been complicated by rainy weather and unstable debris.

What is the latest?

• At least four people were killed, but authorities say the figures could rise further.
• Officials say 159 people remain missing, while at least 35 people have been rescued.
• Rescue operations are still ongoing, with teams working overnight to search for survivors.
• Firefighters face "extreme risk" in combing through the rubble, as "debris is falling on them," said Miami-Dade Mayor Daniella Levine Cava.

What do we know about the collapse?

A beachfront apartment building partially collapsed around 1:30 am (0530 GMT) on Thursday in the community of Surfside, trapping scores of people.

The 12-story building, called Champlain Towers South, drew travelers from around the world.

The tenants included a mixture of seasonal renters and full-time residents.

Officials in Florida have stressed that it is unclear how many of the building's occupants were inside at the time of the collapse.

The cause of the collapse was also not immediately clear.

Video of the incident appears to show that the center of the building collapsed first, followed by a portion closest to the Atlantic Ocean.

What has the reaction been?

US President Joe Biden approved an emergency declaration on Friday, ordering federal help to supplement state and local response efforts.

"The President's action authorizes the Department of Homeland Security, Federal Emergency Management Agency (FEMA), to coordinate all disaster relief efforts," the White House said in a statement released on Friday.

According to the White House statement, FEMA is authorized to identify, mobilize, and provide at its discretion the equipment and resources necessary to lessen impacts of the collapse. 

Miami-Dade Mayor Levine Cava told reporters on Friday that despite the dangerous work and threat of rain, rescue teams will stay on site.

"We will continue search and rescue because we still have hope that we will find people alive," said Levine Cava, who described the dedication of the dozens of rescuers on site as "incredibly moving."

"They are totally, totally motivated to find people. They have to be pulled off the shift. That is how motivated they are to continue their efforts," she said.

"The building is literally pancaked,'' Surfside Mayor Charles Burkett said. "That is heartbreaking because it doesn't mean, to me, that we are going to be as successful as we wanted to be in finding people alive.''

rs, dvv/msh (AP, Reuters, AFP)