CHICAGO (CBS) – Flames lit up the city’s South Side, when two buildings erupted in a fire that required more than 100 firefighters to put out.

As CBS 2’s Mike Puccinelli reports, as of 5 a.m. Monday all the firefighters were gone, but police squad cars remained. Officers were guarding the scene so investigators could get in to try to find out what touched off the fire.

The fire was reported just after 11 p.m. Sunday. The 2-1/2 story residential building at 6606 S. LaSalle St. burned with such intensity that firefighters made no attempt to go inside the building to try and put it out.

It’s not clear where the fire started or if it was deliberately set. The building was engulfed in flames, and even threatened nearby buildings which were slightly damaged.

LaSalle Street Fire

A fire raged overnight in the 6600 block of South LaSalle Street. (Credit: CBS)

Firefighters used ladder trucks to attack the blaze, which was put out in less than an hour. The 25-by-50-foot building was vacant at the time of the fire.

It is not known if the building was evacuated first, or if it had been unoccupied for some time.

No firefighters were injured.

The back of the building next to the one that burned also sustained extensive damage. Debris from the building lined the alley behind it.

The Sun-Times Media Wire contributed to this report.

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