Several fires have mostly destroyed the Moria migrant camp, home to more than 12,000 asylum seekers.
There are no known casualties so far. Authorities are now investigating reports of arson.
Firefighters on Wednesday fought to contain multiple fires at Greece’s largest migrant camp located on the island of Lesbos. Thousands of residents fled from the camp, but were stopped by police vehicles. Most were being guarded by police on a nearby highway.
Moria is home to more than 12,000 asylum seekers, many of whom arrived in 2015 and 2016 after fleeing their homes in Iraq and Syria.
Human rights organizations have urged Athens to transfer migrants from overcrowded centers on Greek islands to mainland centers, which are considered far less crowded.
At least 35 people at the camp had tested positive for COVID-19 as of Tuesday.