Police shot the gunman to death outside a Target store inside Ward Parkway Center in south Kansas City, police spokesman Tony Sanders said.
Target employee Cassie Bradshaw, 19, was in a break room with two other people when they heard shots. Then, her co-workers saw a man in his 50s with a rifle "shooting everywhere," she said.
"It sounded like maybe firecrackers at first but then they got louder and louder and louder, and it sounded like someone shooting a gun," she said.
The string of violence began early Sunday afternoon, when police went to a home to check on an elderly woman relatives hadn't seen for days. The woman was found dead and her car missing, Sanders said.
The car was spotted later in the day at a gas station by an officer, who pulled the driver over and was shot in the arm, police said. The officer, whose wound was not life-threatening, returned fire and shattered the window of the gunman's car.
The car took off and was seen later at the shopping center. The man pulled into a parking space and fired at the cars on either side of him, killing two people, authorities said. He fired more shots, wounding two people, then went inside the mall, Sanders said.
Police did not say how the elderly woman died, or if the gunman was a suspect in her death. But they did say they believed the events were connected.
The mall, one of the city's busiest shopping centers, was shut down and officers were going through each store to see if anyone else might have been involved, Sanders said.
The gunman and victims' names were not immediately released, and conditions of the wounded were not available.