The shooting occurred at around 10 p.m. at the Humidor in Lisle on Ogden Ave. Officers arrived and found "several victims who required life saving aid."
Retired Trooper Greg Rieves, 51, and the shooter, a 51-year-old woman later identified as Lisa V. McMullan of Chicago, were both pronounced dead, police said.
Rieves died at an area hospital. He had retired from the state police in March of last year after 25 years of service.
Rieves is now remembered as a happy man who lived life to the fullest.
"Greg has always been special to the family," said Carolina Mosley, his cousin. "He has always had a bright smile and he was always the coolest kid."
Investigators said Rieves was watching TV with two other ISP troopers when McMullan pulled out a gun and shot him in the back of the head.
Police said McMullan, who had no criminal history and a valid FOID card, then fired several rounds at the other two troopers before she turned the gun on herself.
Retired Trooper Lloyd Graham, 55, and active Trooper Kaiton Bullock, 48, were injured and taken to hospitals.
Bullock, a 22-year veteran of state police, was off-duty when he was shot, police said.
Both are expected to recover.
WATCH: ILLINOIS STATE POLICE OFFICIALS SPEAK ON SHOOTING VICTIMS
The shooting was caught on surveillance cameras.
"We ask that everyone will pray for us, the other two officers and for her family," said Mosley.
Rieves and McMullan both went to Proviso East High School in Maywood.
Family members said McMullan was often at the Lisle cigar bar, where Rieves and his friends would hangout.
But police do not know why she pulled the trigger.
"We do thank God that no one else was killed," Mosley said.
Family and friends remember Rieves as a baseball-loving father, a son and a state trooper who served protecting the community for more than 20 years.
"Illinois State Police family stay focused on the health and wellness of all of those who have been impacted by this horrible violence," said Illinois State Police Director Brendan Kelly.
Staff from The Humidor issued a statement on the lounge's Facebook page, saying "Thank you for your messages. The staff is fine. ... We look at all our customers as family and we ask you to pray for the victim and the speedy healing of the injured."
The Lisle location was closed Saturday.