COLUMBIA, Md. (AP) -- Someone armed with a gun opened fire at a busy shopping mall in suburban Baltimore on Saturday. Three people died, including the person believed to be the shooter, police said. The shooting took place at the Mall in Columbia, a suburb of both Baltimore and Washington, according to Howard County police. Someone called 911 at around 11:15 a.m. to report a shooting at the mall. Police responded to the scene and found three people dead, including one person who was found near a gun and ammunition. No details were released about their identities. Police said they believed that one of the people found dead was the shooter. Two people with minor injuries were transported to a hospital for treatment. The mall is at the center of the town and typically opens at 10 a.m. on Saturdays. It was busy with shoppers and employees when shots rang out before noon. Joan Harding of Elkridge, Md., was shopping with her husband, David, for a tiara for their granddaughter's 18th birthday. She said she heard something heavy falling, followed by gunshots and people running. "My husband said, 'Get down!' and the girl that worked in the store said, 'Get in the back,' " Harding said. That is where they hid until police gave the all-clear. At a news conference, Howard County Police Chief William J. McMahon said police are relatively confident that there was only one shooter. "We don't know a motive yet," McMahon said. "We are very confident that it was a single shooter, and there was not another shooter in the mall." The mall was closed to the public as police went store to store looking for people who might still be hiding, McMahon said. He said the shooting occurred at a store on the upper floor. Witnesses said they heard a succession of gunshots fired near the food court on the first floor of the mall. People were directed out of the mall and into a parking lot, where some boarded a bus and others walked toward their cars. Some people were seen crying. McMahon said detectives were interviewing witnesses as they emerged from the mall to try to get a better picture of the events that had unfolded. Laura McKinzles of Columbia works at a kiosk in the mall. She said she heard between eight and 10 gunshots, followed by people running and screaming. She ran into the backroom of a perfume store and locked the door. Allison Cohen, who works at the apparel store "Lucky Brand Jeans," said she always felt safe at the mall. "I truly never thought something like this would ever happen here. It's really, really shocking," Cohen said.