MIAMI, Florida (AFP) - A series of explosions shook a propane gas plant in central Florida, injuring eight people, with three in critical condition, local authorities said on Tuesday.

"The balance that we have is eight people were injured, and at least three in critical condition. They are workers at the plant," John Herrell, spokesman for the Lake County Sheriff's Office told the press.

Herrell said the explosions began around 10.30pm on Monday when "a crew of 24 to 26 people was working the overnight shift." The blasts set off a huge fire at the Blue Rhino plant, which firefighters contained early Tuesday.

A small leak in one of the largest tanks continued on Tuesday, but did not pose a risk to the city of Tavares where the plant is located, according to authorities.

"We continue to monitor the situation and assist the local emergency responders as requested," said Florida Division of Emergency Management Director Bryan Koon, categorising the explosion as an "isolated event."

Mr Richard Keith, head of the Tavares Fire Department, told reporters "we don't think there was any act of sabotage or anything like that." The explosion was likely due to equipment or human error, he said.

Some nearby areas had been evacuated overnight, but restrictions have since been lifted.

The Orlando Sentinel wrote that the first explosions before midnight blew the roof off the plant, which was followed by more blasts early Tuesday.

Residents told local media they had seen a "giant fireball" in the sky.

Several injured people were taken to hospitals in Orlando and nearby areas.

Authorities, who at first said as many as 15 workers were missing, said later that they had all been accounted for.