07/31/2013 02:31 pm ET

Water Tank Falls From Brewster Building In Lakeview, Injuring 3

A century-old wooden water-retention tank fell Wednesday morning from atop the historic Brewster Building in Chicago's Lakeview neighborhood, sending three people to area hospitals.

According to Lakeview Patch, the structure fell about 100 feet from the 9-story building at 2800 N. Pine Grove Ave. around 9:45 a.m. Wednesday.

Two of those injured in the collapse were in serious condition and the other was in critical condition, NBC Chicago reports.

The building housing the approximately 15-foot-tall tank had failed a February 2010 inspection, according to DNAinfo Chicago.

When the massive tank fell, the water it was filled with surged out and knocked down a teacher at a nearby day care school, DNAinfo reports.

The Chicago Tribune reports the critically injured woman had been moving out of the adjacent building and was struck by debris. "She looked unresponsive," a witness told the paper. The woman's boyfriend was also injured when a "wall of water" hit him.

"I heard this noise, and I full on thought it was a bomb and it was a really loud noise," another witness told ABC Chicago.

The cause of the tank's collapse is under investigation.