Two firefighters were killed and 14 others were injured -- six critically -- after being trapped in a vacant burning building on Chicago's South Side on Wednesday.

Ten firefighters are listed in in stable condition following the blaze at an abandoned dry cleaners, where a wall collapsed as crews fought the fire at the one-story building, MyFoxChicago.com reports.

Dozens of firefighters sifted through the rubble to find their comrades, and then rushed them to nearby hospitals. 

The fire started at about 7 a.m. local time and a "mayday" call went out when the wall collapsed. Ten ambulances rushed to the scene.

The blaze occurred on the 100th anniversary of the Union Stockyards fire that claimed the lives of 21 Chicago firefighters in 1910. In all, 24 men in that fire in the meatpacking operation at a Morris & Co. plant.

"This is a family and it's very hard," Fire Department spokesman Larry Langford said. "You had guys who were coming in off duty to help dig. Everybody wanted to help find people. It's very hard on folks."

The brick building had been abandoned for several years and utilities had long been cut off. Langford said the fire's cause was uncertain but that it was possible that squatters had been living in the building and been burning debris inside to keep warm.

"The fire had no other way of starting," he said.

The Associated Press contributed to this report.

Click here for more on this story from MyFoxChicago.com.