One of the suspects was killed, but the another is still on the loose Wednesday.
Police say they believe the suspect -- who managed to escape -- could be armed.Officials have not released a description.
Some residents in the South Side Bridgeport neighborhood awoke early Wednesday to gun shots between the two robbery suspects and Chicago police officers. The shooting happened at a convenience store near 31st Street and Union.
Shattered glass, crime tape and numbers marking evidence lined the parking lot of the J.J. Peppers store later Wednesday.
"There was police everywhere. They looked like Spiderman on top of the buildings looking," said neighbor Ramona Rivera, who also said she popped out of bed when she heard a 'Bang, bang, bang' outside of her home.
"I woke up and my mom was on the floor like, 'Don't get up! Mona, don't get up!'" Rivera said.
Officials say two police officers spotted two masked men with hooded sweatshirts at approximately 1:30 a.m. Wednesday walking into the store. So, the officers reportedly became suspicious and chased the men into the store and stopped them during the alleged robbery.
"At 1:30 in the morning wearing hoodies when its 70 degrees outside? It's a little bit unusual," said Fraternal Order of Police Spokesperson Pat Camden. "Very alert, very brave officers, stop to investigate, see one of the individuals jump over the counter. They know it's a robbery in progress."
Police say one of the suspects, identified by the medical examiner as 30-year-old Jeff Wilson, shot at the officers who then returned fire, killing him.
Wilson, who lived near 100th and Normal, was paroled last October after serving time for a 2005 robbery attempt. The medical examiner says he died from a single gunshot wound to the chest.
The other man headed to the back of the store and appeared to barricade himself.
"Everyone in the corner house had to get out of the house because the back door was by their bedroom window, so the SWAT guys were in the bedroom window looking out," said Mark Vlzonis, neighbor.
After more than five hours in standoff mode, police discovered the man had escaped through a back door. Officers threw stun grenades in the store -- which disorient a person's senses -- just in case the man was still inside.
A clerk who was in the store during the robbery escaped the danger. Witnesses say he jumped through the gun-shattered window. Police at the scene would not allow ABC7 Chicago to speak with him but said the man was doing OK.
Chicago police also say the two officers inside the store were taken to Northwestern Memorial Hospital as a precaution. They are expected to be OK.
A few streets in the area were shut down Wednesday morning because of police activity, but they reopened at approximately 7 a.m.
Some CTA buses were rerouted temporarily, but service soon returned to normal.
Residents describe the neighborhood as quiet and safe with a police station a couple blocks away.
"They come here all the time, cops. They'd be crazy to try to do that at that time. I don't know how the other guy got away," said Tony Oberlin, neighbor.
"It's not very common because of the police station, and they usually circle the area a lot. Very often," said Trenell Adams, witness.