At least one person has died and 51 others are unaccounted for after the collapse overnight of a 12-storey residential building north of Miami, Florida, officials say.

Rescuers are combing the rubble in the search for survivors and were seen pulling a boy out alive.

It is unclear how many people were in the building at the time.

The complex in the town of Surfside was built in 1980. Out of 130 units, about half were affected by the collapse.

Fifty-one people believed to have been living in the building have not yet been contacted, County Commissioner José Díaz said.