A derailed tanker train exploded and decimated a village in north-eastern Bulgaria, killing seven people and leaving at least 29 injured, many with severe burns, the Interior Ministry said.
Authorities said about 50 buildings in the village of Hitrino were destroyed when containers of gas exploded early on Saturday.
Hitrino Mayor Nuridin Ismail said children had been buried under the rubble of a house that collapsed.
Two tanker cars carrying propane-butane and propylene derailed at the station in Hitrino, hit nearby electric lines and exploded, police officials said. The engine driver survived and has been questioned, police said.
Officials had earlier described the cargo as liquefied natural gas.
The entire village of 800 people was evacuated as a precaution due to the risk of new explosions. Emergency teams started a high-risk operation to reload the hazardous substances.
Prime Minister Boiko Borisov, who arrived at the scene, urged citizens to donate blood to address shortages at nearby hospitals.
"There will be more casualties," Borisov told reporters.
He said several people suffered more than 90% burns and that damage from the explosion was extensive.
The train had been travelling from the Bulgarian Black Sea port city of Burgas to the Danube city of Ruse.
The government declared Monday a national day of mourning for the victims of the blast.