A bomb exploded at a bus stop in central Moscow on Monday, December 7, leaving four people injured, Russian media report, according to Digital News World.

The device was thrown from a car passing by the stop. Three women and a men were hurt, none of them seriously, RBC reports.

Authorities suggest the bomb was a home-made one.

Located just 1 km away from the Red Square and the Kremlin, the street where the incident took place remained sealed off for hours on Monday evening.

Security is now stepped up across the Russian capital, with security officials warning of possible terror attacks.