It happened at Lawlor's Bar in the 3600-block of W 111th Street, CFD said.
A 31-year-old man, a 45-year-old man and a 41-year-old woman were all transported to Little Company of Mary Hospital after snorting an unknown substance, Chicago police said.
Two other people were taken to Christ Hospital, fire officials said, but no other details were provided on them at this time.
All were said to be in fair to serious condition and have since been stabilized.
Lawlor's Bar issued a statement regarding the incident:
"Lawlor's is a small neighborhood establishment that's been a member of the Mt. Greenwood community for 15 years. We are shocked and concerned about what took place this afternoon and are praying for the health and well-being of everyone involved. We are working with the Chicago Police Department during this active investigation."