Minneapolis, Minn. (CNN) -- An explosion and fire at an apartment complex in Minneapolis left 13 people hospitalized Wednesday. Six are in critical condition, Minneapolis Fire Chief John Fruetel told CNN.
Most of the injuries are from burns and "trauma of people that came out through the windows," said Robert Ball, a spokesman for Hennepin County Emergency Medical Services. Officials don't know whether people jumped out, fell or were pushed out by the explosion.
The three-story building was destroyed, with the roof and the second and third floors collapsing, Fruetel said.
Heavy flames were coming out of the second- and third-story windows.
Hours after the incident, firefighters were still working to contain the blaze. They tried to enter the building but were able to get in only a little way.
Freezing weather in the city presents challenges and dangers for firefighters, since water used to try to put out the fire can quickly turn to ice, Ball said.