One person died and 57 were injured after two explosions rocked an unlicensed liquified petroleum gas filling station just north of Romania's capital Bucharest late on Saturday, officials said.

Most of the injured were firefighters who rushed to the station to extinguish the blaze from the first explosion before the second occurred.

Among the injured -- some with severe burns -- were 39 are firefighters, two police officers and two gendarmes, Raed Arafat, head of the emergency department, said on Sunday.

"Overnight we transferred two firefighters and two civilians abroad (for treatment) and more will follow," Arafat said in a statement.

The four were transferred to Italy or Belgium, according to the defence ministry.

It was not immediately clear what caused the blasts in Crevedia, a commune of villages, and prosecutors have opened an inquiry.

"We know that the station was no longer working, so it clearly didn't have a permit to function," Arafat said.

The fire also forced the evacuation of people within a 700-metre (770 yards) radius.

"I'm profoundly saddened that the explosions in Crevedia resulted in victims," President Klaus Iohannis wrote on Facebook, calling it a "tragedy".

Anger has flared repeatedly in the EU member state over a lack of official oversight to ensure compliance with safety regulations.

In 2015, a blaze ripped through a Bucharest nightclub after fireworks were let off, killing 64 people.