Unknown assailants early Friday threw firebombs into a migrant camp on the Greek island of Chios, and beat up two volunteers, the state Athens News Agency said.
According to the agency, two tents at the Souda camp were destroyed and around 150 panic-stricken residents including women and children were forced to flee to safety.
A group of 30 assailants subsequently beat up two volunteers helping at the camp, ANA said.
Police did not immediately confirm the incident but a local official speaking on condition on anonymity said the island was "seething" over the presence of some 4,000 refugees and migrants.
This official also noted that lawmakers from the Greek neo-Nazi party Golden Dawn had visited Chios just days earlier.
"We cannot exclude that far-right groups are seeking to exploit local anger," the official told AFP.
Tempers had also flared the previous evening after groups of migrants broke into a spirits merchant and stole fireworks from another shop.
According to police, they then set the fireworks off, targeting local homes and cars.
Three Algerian teenagers and an Iraqi in his forties were arrested over the incident.
According to Greek media, Thursday's attack was a reprisal. The assailants climbed atop a medieval fort overlooking the camp and threw heavy rocks on the tents below.
The situation on Chios is similar on other eastern Greek isles sheltering over 16,000 migrants and refugees who are unable to continue their journey to north and western Europe.
The island camps have a nominal capacity of fewer than 7,500 people.