Dozens killed and injured in explosion at Russian petrol station

A powerful explosion rocked a gas station in Russia's city of Makhachkala, located in the Caucasian Dagestan region, killing 30 people and injuring 100 others.

The explosion, which occurred Monday evening, caused a major fire, which spread to an area of more than 600 square meters (6,458 square feet), region's Governor Sergey Melikov said in a statement.

"The cause and nature of the explosion are being established. According to preliminary data, the tanks standing in front of the gas station detonated, resulting in a fire," he said.

The governor announced emergency in the Kumtorkalin district where the incident took place.

Two of the eight fuel tanks exploded, causing massive damage.

More than 70 people with fire-extinguishing equipment were involved in dousing the fire.

Dagestan's authorities also announced a day of mourning following the incident.

A criminal case has been opened on the provision of services that do not meet security requirements.

Russian President Vladimir Putin offered condolences to the relatives of victims and conveyed wishes of speedy recovery to those injured.