A group of men attacked fellow passengers with knives after being scolded for traveling without tickets on a tram in eastern Moscow on Monday.
The trouble started when five men boarded the rear door of tram No. 8 at a bus stop at 19 Shosse Entuziastov around 8 a.m., police said. The tram driver and several passengers reprimanded the men, telling them to buy tickets and go through the turnstile at the front of the tram.
"A conflict broke out involving knives, and three passengers were stabbed," police said in a statement. "In addition, one victim was struck on the head with what appeared to be the handle of a pistol."
The attackers fled, and four passengers were hospitalized. No information was given about their specific injuries.
The police were searching for the attackers, who were described as having Caucasus features, and have appealed to the public for help.