A fire ripped through a rowhome in the Fairmount section of Philadelphia and killed eight children and four adults on Wednesday morning in what local reports are calling the deadliest fire in the city in more than a century.

WPVI-TV reports that fire officials say the number of fatalities could increase as they continue recovery efforts.

“Without a doubt one of the most tragic days in our city’s history,” Mayor Jim Kenney said at a news conference near the location of the fire on Wednesday afternoon. “Losing so many kids is just devastating… Keep these babies in your prayers.”

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The fire occurred before 6:30 a.m. in a public housing unit where 18 people were reportedly living in the upstairs unit—Unit B. Eight more people lived in the first-floor unit—Unit A.

The Philadelphia Housing Authority reported that as of the most recent occupancy recertification, only 14 people were living in the upper unit—which is where most, if not all, of the fatalities, occurred. The area remained blocked off until late Wednesday evening.

Mayor Kenney said that people should withhold judgment about the living conditions.

“You don’t know the circumstances of each and every family, and maybe there were relatives and family that needed to be sheltered,” Kenney said. “Obviously the tragedy happened, and we all mourn for it. But we can’t make judgment on the number of people living in the house because sometimes people just need to be indoors.”

Source: Children death toll in Philadelphia row house fire rises to 8