An explosion on a freight train carrying chemicals and oil products hurled part of a railcar into a residential block in southern Russia, injuring 27 people of whom 13 were taken to hospital, officials said.

The Federal Investigative Committee said 69 railcars carrying sodium chloride, gasoline, fuel oil, propane and other goods derailed following an onboard fire on Thursday near Belaya Kalitva station in the Rostov-on-Don region, around 1,000km south of Moscow.

The blast hurled part of a railcar into the sixth floor wall of a residential block. No fatalities have been reported.

Despite the toxic contents of railcars, Emergencies Ministry's spokesman Ilya Konstantinov said that there was no danger neither for the residents, nor for the workers at the site.

"At the moment there are no dangers, neither from toxic substances, nor of another explosion or fire spreading across, for the residents as well as for the people working at the fire site," Konstantinov said.

A criminal investigation has been launched into possible safety breaches.

Source: Agencies