Four people were injured early on Thursday, Nov 8, when a grenade thrown by an unidentified attacker exploded outside a nightclub in northern Moscow, police said, according to RIA Novosti.

The incident occurred at around 02.00 am Moscow time (22:00 GMT on Wednesday). The attacker, who was reportedly drunk, tossed the grenade at security guards after they did not allow him to enter the club.

“According to a preliminary investigation, four people were injured in the blast,” police said.

Three of the victims were hospitalized with serious injuries while the fourth person received minor medical treatment at the scene.

Police are searching for the suspect who fled the scene after the explosion.