At least 21 people, including whole families and children, were killed when a fire broke out at a residential building in a refugee camp in northern Gaza on Thursday, according to Palestinian authorities in Gaza, writes CNN.

The fire broke out in Jabaliya refugee camp, Gaza’s Interior Ministry said. A preliminary investigation found a large amount of gasoline inside the building, which contributed to the escalation of the fire, it added.

Everyone in the building was killed, ministry spokesman Iyad Al-Bazm said.

The dead included entire families, local media reports said, listing a doctor, a local government official and a pharmacist, and their wives and children among the victims.

Hussein AlSheikh, the Palestine Liberation Organization’s executive committee secretary general, called on Israel to open the Erez crossing to allow the wounded to be transported to hospitals outside Gaza.