Four young people, including a female student...

No one was hurt in the attack.

The source said that the assailants fled in a Mitsubishi Lancer after opening fire at the Bibiryevo post.

"The vehicle was blocked off after a chase," the source said. "There were two young men and two girls in the car."

The source added that three of the detainees were born in 1987 and one in 1990. One of the girls is a student at a Moscow economics and law college.

The weapon used in the attack has not yet been recovered.

MOSCOW, March 23 (RIA Novosti)