Unknown assailants fired two shots at a police bus in Athens Tuesday morning, according to Greek radio broadcasts, reproted dpa.
No injuries were reported in the incident, which occurred in the Athens suburb of Goudi. One shot hit a tyre while the second hit the side of the vehicle. The bus driver managed to bring the bus to a safe halt, the broadcasters reported.
Separately, unknown individuals set fire to four cars and a motorcycle in various parts of Athens overnight.
Athens has been subjected to sporadic violent protests ever since the police shooting of a 15-year-old boy on December 6.