Migrants on the Greek island of Lesbos started a fire at an overcrowded facility and clashed with police in an incident that killed at least one person.

The migrants set a fire at an olive grove outside the camp Sunday evening and then started another blaze inside the camp, Greek police spokesman Lt. Col. Theodoros Chronopoulos told the Associated Press. One burned body was brought to a local hospital and there was information about a second.

“The situation is tense,” Lesbos Mayor Stratis Kytelis said. “There is information about a dead mother and her child. We haven’t been able to confirm that yet.”

About 12,000 mostly Afghan migrants are housed in a facility designed for 3,000.

Mainland Greece and the surrounding islands have been an epicenter of the migrant crisis engulfing Europe in recent years.