A total of 159 people are still unaccounted for after an oceanfront apartment building collapsed near Miami, killing at least four people.

The search at the 12-storey Champlain Towers South building just a few miles north of the Florida city’s South Beach is taking a toll on relatives who can do little but hope that their loved ones will somehow be found alive.

Scores of rescuers are using diggers, drones, microphones and their own bare hands to pick through the mountain of debris.

Miami-Dade county mayor Daniella Levine Cava said there is still hope of finding survivors in the rubble more than 24 hours after the building collapsed.

Assistant Miami-Dade county fire chief Raide Jadallah said rescue operations had continued throughout the night, with 130 firefighters working at the site.

Building collapse in Miami
A group of people pray together on the beach next to the site of the collapse (Miami Herald/AP)

Police director Freddy Ramirez has said authorities are working with the medical examiner’s office to identify the victims.

Rachel Spiegel is awaiting an update on her missing mother, 66-year-old Judy Spiegel, who lived on the sixth floor.

“I’m just praying for a miracle,” Ms Spiegel said. “We’re heartbroken that she was even in the building.”

Jeanne Ugarte was coming to grips with what she feared was a tragic end for her friends Juan and Ana Mora and their son Juan Jr, who was visiting his parents in the tower.

A tribute to the missing
Local people pay tribute to people missing in the collapse (AP)

“I know they’re not going to find them (alive),” Ms Ugarte said. “It’s been too long.”

Hopes are resting on how quickly crews can complete their grim, yet delicate task in Surfside.

“Any time that we hear a sound, we concentrate in that area,” assistant fire chief Jadallah said.

“It could be just steel twisting, it could be debris raining down, but not specifically sounds of tapping or sounds of a human voice.”

Surfside mayor Charles Burkett said crews are doing everything possible to save as many people as they can.

The site of the collapse from afar
As many as 159 people are missing (AP)

“We do not have a resource problem, we have a luck problem,” he said.

Officials still do not know exactly how many residents or visitors were in the building when it fell, but they were trying to locate 159 people who were considered unaccounted for and may or may not have been there.

Eleven injuries were reported, with four people treated in hospital.

Miami-Dade mayor Ms Cava said rescuers were at “extreme risk” going through the rubble.

“Debris is falling on them as they do their work,” she said. “We have structural engineers on-site to ensure that they will not be injured, but they are proceeding because they are so motivated.”

A building collapse
Scores of rescuers are still looking for survivors (AP)

While officials said no cause for the collapse early on Thursday has been determined, Florida governor Ron DeSantis said a “definitive answer” is needed in a timely manner.

Video showed the centre of the building appearing to tumble down first, followed by a section nearer to the beach.

The missing included people from around the world.

Israeli media said the country’s consul general in Miami believed 20 of its citizens are missing.

Another 22 people were unaccounted for from Argentina, Venezuela, Uruguay and Paraguay, including relatives of Paraguayan first lady Silvana de Abdo Benitez.