The explosion occurred on a tanker in the port of Makhachkala; three people remain missing and a search is underway.

Axar.az reports citing the RIA Novosti that the press service of the Federal Agency For Maritime, River Transportation said.

By the information, the explosion was caused by an air-gas mixture on the tanker catching fire. Moreover, Rosmorrechflot clarified that the explosion occurred in the engine room.

"Supposedly, five people were injured, two were taken to hospitals, three people remain missing - the search is underway," Rosmorrechflot added.

The details of the incident are establishing.