Fire in an apartment complex killed five people early Saturday, four of them children, as water sprayed on the flames by firefighters turned to ice in bitterly cold weather.

Flames already were billowing from both floors of the two-story townhouses when firefighters arrived. Firefighters tried to force their way into the building, but turned back when the structure started to give way, said Fire Battalion Chief Doug Smith.

Two children standing outside the building told firefighters that their relatives were trapped inside, Smith said.

"One child said that she could hear one of the children screaming for about 30 seconds, and then that stopped," Smith said. "That was all they heard after that."

He said the victims were a 40-year-old woman and four children ages 5, 7, 10 and 12. Authorities believe the victims may have been related; Smith said some of the children had the same last name.

No one else was injured.

At least three of the apartment complex's 10 units were destroyed, Smith said. He did not know how many people lived in the building.

Twenty-one fire trucks were sent to the blaze, said Fire Lt. Shannon Morrison.

The temperature was in the teens Fahrenheit.

"A lot of the time the water, it was freezing to ice when it hit the pavement. We had to call for a salt truck," Smith said.

Fire officials are investigating the possibility that the fire started in the living room, but the cause did not appear to be suspicious, Smith said.