The Milwaukee Fire Department (MFD) responded to a fire at the former Northridge Mall building on Tuesday.
According to the MFD, the call came in after 5 p.m.
Due to the hot weather, MFD says it was hard to ventilate the building. The call was upgraded to the second alarm level.
An ambulance was also seen heading to the area. MFD was assisted by North Shore fire and the Wauwatosa Fire Department units.
No firefighters were injured.
The building suffered extensive damage and the cause remains under investigation, MFD says.
The fire comes in a district looking to rebound from decline over the course of recent years. "We don't even have an alderwoman to deal with this now," said District 9 resident Tim Hoeller. "That has to be corrected first and alderperson's have to take the building down."