Ajax and AEK Athens fans clashed in Greece's Olympic Stadium ahead of the Champions League match on Tuesday. According to IndependentGreek supporters "reportedly launched flares and a missile or a bomb of gasoline", which exploded near supporters of the Dutch club.
Here is another angle of the explosion:
According to the Associated Press, "the riot police dispersed local supporters who threw plastic bottles and other objects at visiting supporters.
The violence also erupted before the match in Athens, as Ajax won 2-0. From the AP:
Rival Greek supporters were involved in the violence near the city's police headquarters. Traffic was blocked after young people threw gasoline bombs at rival supporters and police.