Criminal investigation underway after fire injures 2 outside Lincoln Park Zoo's Cafe Brauer: CFD

CHICAGO (WLS) -- The Chicago Fire Department says an early morning fire at Lincoln Park Zoo has prompted a criminal investigation.

The fire broke out in a shed outside the zoo's historic event space, Cafe Brauer, on Friday morning.

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CFD responded to the scene around 4 a.m.

Firefighters say a propane tank had been opened.

A Chicago firefighter and one other person had minor injuries.