TACOMA, Wash. – A gunman opened fire inside a busy shopping mall yesterday, wounding at least six people and taking three others hostage in a music store before a SWAT team arrested him, authorities said.

Witnesses described seeing a 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.

A Tacoma Police spokesman, Mark Fulghum, said the suspect was a young man, but he had no other details or possible motives.

A SWAT team arrested him without firing a shot, and police were interviewing the victims and hostages to determine what happened during the nearly four hours he was inside, Mr. Fulghum said.

While the suspect was still in the Sam Goody music store, employee Joe Hudson was able to pick up the 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.

Susan Serdeau said she also called her daughter, Kathy Riggans, 24, a manager at Sam Goody, as soon as she heard about the shooting.

“She was upset and scared. She was crying,” Ms. Serdeau said, standing in a parking lot near the mall. “All she would say was that she was okay.”

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

State Patrol and police units from nearby agencies clustered around an entrance at the south end.

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,” Ms. 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.

Ms. Wilson said she heard 15 to 20 shots.

“He was walking backward and shooting. I couldn’t see his face,” she said. “Everyone was running and screaming.”

Betz Dejarnatt, who works at the J.C. Penney store, said workers were herded into dressing rooms and offices, then police took them outside to a parking lot.

Six people were taken to hospitals, most with minor injuries, according to the Tacoma Fire Department’s deputy chief, Jon Lendosky. One person was in critical condition at Tacoma General Hospital, a spokesman, Todd Kelley, said.