Clashes between rival groups of Iraqi migrants broke out on Monday evening at the Moria reception center on the Greek island of Lesvos.
According to a report by the Athens-Macedonian News Agency, the clinic of the reception center was badly damaged when a group of migrants sought refuge in the premises.
There are no reports of injuries.
Correspondents say that the atmosphere at Moria is tense due to overcrowding.
The reception center is designed to house around 3,000 migrants, but there now more than 6,000 living in deteriorating conditions.
Migrant flows continued unabated during the Easter period.
A total of 607 refugees and migrants crossed from the Turkish coast to the northern Aegean islands and were registered at reception centers.
Since Holy Thursday until Tuesday morning, 418 migrants crossed over to Lesvos, 69 to Chios and 120 to Samos.