Referee Anastasio Kakos ordered the Greek Super League match between rivals Panathinaikos and Olympiakos Pireaus at the Olympic Stadium in Athens to be abandoned Sunday with nine minutes remaining.

Fire trucks were called in to extinguish flames after unruly Panathinaikos fans set several sections of the stands on fire. The start of the second half was delayed by 45 minutes as fans pelted police with flares, molotov cocktails, and missiles. When Kakos stopped the game with nine minutes Olympiakos led, 1-0, through Djamel Abdoun’s 51st-minute goal.

When several gasoline bombs exploded near the field, Kakos waved the players off the field. Twenty police officers were injured and more than 50 arrests were made. Panathinaikos captain Kostas Katsouranis said Greek soccer had been shamed.

“That was not soccer,” Katsouranis told reporters. “Certainly it’s one of the worst moments in Greek soccer and I don’t even want to comment on the game. As a team we will just try to get on with the next matches and fight for a place in the Champions League qualifiers.”

Panathinaikos has already been punished once this season for the unruly behavior of its fans. It faces a disciplinary hearing Tuesday.