Tacoma, Wash. ? A gunman opened fire inside a busy shopping mall Sunday, wounding at least six people and taking three others hostage in a music store before he surrendered to a SWAT team, authorities said.

Witnesses described seeing a clean-cut man walking backward through the mall, firing a rifle. At least six people were injured, one critically, as shoppers and store clerks scrambled for cover.

Tacoma police spokesman Mark Fulghum said the suspect was 20 and lived in Tacoma, but he had no other details or possible motives.

The gunman came out of the Sam Goody music store without a gun and surrendered to the SWAT team, Fulghum said. He said police were interviewing the victims and the three hostages – two men and a woman – to determine what happened during the nearly four hours he was inside.

While the suspect was in the music store, employee Joe Hudson was able to pick up a phone call from The Associated Press and say he and others had been taken hostage. He said little more but could be heard telling others that he was talking to the AP.

Police officers walk through the parking lot of the Tacoma Mall in Tacoma, Wash. A man was arrested Sunday afternoon, several hours after apparently walking inside the busy shopping mall where he took three hostages, Tacoma Police officials said.

Authorities said they began getting calls about 12:15 p.m. that shots had been fired inside the Tacoma Mall. The first caller said a gunman “was in the mall, walking along, firing,” Fulghum said.

Inside, Stacy Wilson, 29, of Bonney Lake, heard a popping noise and turned around.

“I saw the gunman randomly shooting. I ran with a group of women to Victoria’s Secret,” Wilson said. She said they crouched behind a wall in the store, and when the shooting stopped, an employee ran out and closed a security gate at the front.

Wilson said she heard 15 to 20 shots.

A man told KING-TV the gunman was smiling as he fired an assault rifle in bursts of four to five shots.

The man said he told his daughter and grandson to run and then hid in the back of a store with his wife and granddaughter. He says they helped a woman who was shot in the leg, bandaging the wound and wrapping her in blankets.

Six people were taken to hospitals, most with minor injuries, according to Tacoma Fire Department Deputy Chief Jon Lendosky. One person was in critical condition at Tacoma General Hospital, spokesman Todd Kelley said.