MILWAUKEE (AP) — Residents jumped from the windows of a four-story apartment building in Milwaukee during a Mother’s Day fire that killed four people, critically injured four others and grew so intense that the blaze outmatched the first firefighters to arrive, authorities said.

Ladder trucks were used to rescue other residents from windows while some firefighters inside the burning building crawled on hands and knees to get people out, Milwaukee Fire Chief Aaron Lipski said Sunday. In all, about 30 people were rescued.

Authorities have not said how the fire might have started.

Lipski said the building did not have a sprinkler system and was built in 1968, predating a law that would have required one, according to the fire chief.

“If we had sprinklers in the buidling we would have stopped the fire very, very small. We would not of had to have people jumping out of windows,” he said.

Several other residents were treated for lesser injuries in the fire that began sometime before 8 a.m. The blaze rendered the 85-unit building uninhabitable, displacing an estimated 200 people.

James Rubinstein, a resident in the building, said he jumped to the ground floor.

“There was so much smoke. I climbed out the courtyard with my cat in my backpack,” Rubinstein told television station FOX6 Milwaukee.

Emergency operaters received calls that people were trapped and jumping to escape. The first firefighters to arrive were “far, far outmatched” by intense flames, Lipski said.

Authorities did not immediately release the identities or ages of the victims. Lipski said the fire began in a common area and spread to multiple floors.

Eddie Edwards, another resident of the building, said he also jumped to escape.

“I wasn’t thinking about nothing but getting away,” he told Milwaukee television station WISN. “Getting out and saving everyone’s life. It was a scary moment.”