Around 20 homes were smashed and many of the residents of the village of some 800 people were evacuated.
Around 20 homes were smashed and many of the residents of the village of some 800 people were evacuated, Nikolay Nikolov, the head of fire safety and civil defence at the police said.
Nikolov said firemen were looking for survivors.
The train was carrying 20 tankers of propylene gas and four tankers of propane butane. It derailed at the Hitrino railway station and the train's two last tankers hit a power line, local police spokeswoman Assia Yordannova said.
The blast occurred at 5:37am (0337 GMT) at the village, located about 100 kilometres (60 miles) from Varna, Bulgaria's main port on the Black Sea.