Crews are still on the scene of a house fire that killed five people in Baltimore early Thursday morning.

According to officials, flames broke out shortly after 2 a.m. in a two-story rowhouse in the 5600 block of Denwood Avenue in East Baltimore.

There were 10 people in the house, and five died in the fire. Officials said that four of the victims were children.

WBAL and WMAR reported that a sixth person jumped out of a second-floor window to escape and that one firefighter fell through the floor, from the second story into the basement.

The home was badly damaged in the blaze; damage estimates have not yet been released. Officials said the flames spread quickly and took nearly two hours to extinguish.

The cause of the fire remains unknown. Fire officials are combing through what is left of the house in hopes of determining the cause.