Police are searching for a gunman who shot and killed a man and wounded a second inside the Orland Square Mall in Orland Park, Illinois, on Monday night, sending terrified shoppers running for their lives, the Chicago Tribune reports. Cops say they don't know the motive for the shooting, but they believe the gunman knew the victim. The identity of the victim, who is said to be 19 or 20, has not yet been released. The suspect is described as a male, about 6 feet tall, wearing black clothing and blue jeans. Deputy Police Chief Joseph Mitchell called the shooting an “isolated incident.” Rana Alkilani, who was shopping with her four children, heard the gunshots. “We were panicking,” said Alkilani, who grabbed her children and fled. “It’s hell…You feel like you’re going to die.” According to the Tribune, police responded to a call at 6:45 p.m. of shots fired near the mall’s food court, where detectives later recovered numerous shell casings. The victim had stumbled away from the scene, and was found near an escalator by the store H&M, police said. He was taken to Advocate Christ Medical Center in Oak Lawn where he died, the Tribune reports. Another victim, who suffered a graze wound, was also was taken to Christ hospital. Detectives are reviewing surveillance footage from inside the mall, and police and SWAT teams are searching the area. “The Orland Park Police will not rest until [the shooter] is in custody,” Mitchell said.