The attack was behind the Frontier restaurant near Cortez and Milwaukee and all three victims worked for the restaurant.
All three were in stable condition Friday morning.
It was just after 8 p.m. when an employee was out back of the restaurant on a smoke break. The restaurant owner says the workers saw at least four men trying to steal another worker's car.
There was a scuffle and other employees ran outside to see what was going on.
"There were five guys breaking into a car across the alley," said restaurant owner Mark Domitrovich. "And it happened to be one of the employees that worked here. And they went outside to find out what was going on. A bunch of people went out there. And the next thing you know shots were fired and three people got hit."
Neighbors who live in the area say they heard the shooting.
"We heard some noise, some voices and yelling and then there was a little silence and we heard two gunshots, a pause and three more," said Lauren Wickel.
The three employees shot -- a manager, a bartender and a cook -- were rushed to an area hospital as the suspects escaped.