The police in Greece said on Wednesday they had arrested 12 migrants suspected of starting a mass brawl in a camp on the island of Samos three days earlier.
Three of them, including a 15-year-old, are suspected of stabbing three people and face charges of attempted murder, while the others are suspected of arson and taking part in violence.
The fight between Afghan and Syrian migrants began in Vathy, the island capital, on Monday night.
It spread to the camp on the hillside above the town and eventually a fire broke out there.
Police used tear gas to subdue the crowd and, alongside the three stabbing victims, eight others were treated for respiratory problems.
Spates of violence frequently erupt on the Greek Aegean islands hosting a large migrant and refugee population.
The camps on Samos, Lesbos, Chios and Kos are hopelessly crowded and the situation became worse following a spike in arrivals.
For instance, the camp in Vathy was built for 650 people, but some 5,700 have been stranded there for months in miserable conditions.
It is similar in other camps serving as so-called hotspots, where applicants for asylum in the European Union (EU) are processed.
Under an EU-Turkey deal from 2016, true refugees are allowed into the bloc, while those rejected are returned to Turkey. (dpa/NAN)