As many as 29 have been left injured by the explosion in Saturday morning's northeastern Bulgarian village of Hitrino, outgoing Health Minister Petar Moskov has said.

Sixteen of them have been hospitalized, nine are still in a facility in the nearby town of Shumen, while the others have been taken to hospitals in the Black Sea city of Varna, Moskov has told reporters in an emergency briefing aired by bTV station.

A blast of cisterns transporting liquefied petroleum gas and propylene has left at least five injured, damaging nearly two dozen buildings.

Four of the patients are very heavily injured while three are in critical condition, according to Moskov. Thirteen have been released from the hospital.

"There is no shortage of blood and blood products," the minister has said, thanking citizens for donating blood upon the calls of Prime Minister Boyko Borisov and local authorities.

Rescuers are still looking for people trapped under the debris, having pulled out at least 12 people.