Chicago police and fire officials responded about 4 a.m. to a fire reported in a 22-story commercial building at Wabash and Madison, in Jewelers Row.
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The high-rise is known as the Mallers Building, located at 5 S. Wabash, and it houses numerous jewelry stores.
The fire broke out on the 10th floor. No one was found inside, as firefighters searched the building.
The blaze was raised to three alarms, meaning more equipment was brought in to put it out. Flames were visible from the street level at one point.
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By 5:30 a.m., the fire had been extinguished.
Two firefighters were overcome by heat and were being treated at Northwestern Memorial Hospital, but no other injuries were reported later Thursday morning, Chicago fire Commissioner Richard C. Ford said.
He said the fire was difficult to put out because of its location in the high-rise building. There were about 200 firefighters on the scene, Ford said.
"My shop looks OK," jeweler Ilya Kunin said. "I checked the cameras. Thank god it looks to be under control."
Kunin has a shop on the 12th floor. He said jewelry repair shops and manufacturers often work with gas and torches.
"I mean, listen, mistakes happen. It's like when we leave the shop, I triple check gas is off, everything's off, machines are off, nothing accidentally left on," he said.
Wabash was closed in the area of the emergency response, but the CTA was not affected.
Fire investigators worked to determine the fire's cause later Thursday, and no one else was allowed in the building.
Jewelers hoping to get inside said the building was in the process of installing sprinklers.
Two firefighters were injured and others had to be rescued from the same high-rise during an overnight fire in April of 2018. That previous fire forced jewelers out of the building for an extended period of time.
"We just can't catch a break. I just can't catch a break with this," Kunin said.