The victims are employees of Peoples Energy. They were conducting an underground test at Jackson and Wacker Drive when the accident happened.
The medical examiner's office confirmed that one of those workers died as a result of the accident. It happened just below the street level at the intersection of Jackson and Wacker, right across the street from the Willis Tower
Around 1:45 Wednesday afternoon, the workers were testing a 20-inch main, a steel pipe that slipped and struck those workers. There were initial reports of some type of gas explosion, but Peoples Energy says they were using air compression and there was no natural gas involved.
"There was no gas involved at all. We have two workers who were critically injured and both removed to Cook County Hospital," said Chief Michael Fox, Chicago Fire Department.
"The two employees were in the performance of their duties, they were testing a pipe and an accident occurred," said Bonnie Johnson, Peoples Energy.
"They slipped the first guy out right away, and -- unconscious -- they laid him down. The second guy they couldn't get out; I think it took four or five people. I gotta commend the fire department, they got him out quick," said Todd Hinden, witness.
That second worker apparently is the one who was killed. The first worker is still listed in critical condition at Cook County Hospital. Peoples Energy has not released the names of either of those workers.
The intersection was closed for a couple of hours. It reopened around 3:30 p.m.