The trench coat-clad gunman who killed five people and wounded four at a shopping mall before being fatally shot by police calmly fired a shotgun at his victims and had a handgun, authorities and witnesses said.

Detectives were trying to determine what sparked the rampage at the Trolley Square shopping mall on Monday night.

Salt Lake City police Detective Robin Snyder said the shooter was an 18-year-old from the Salt Lake City area, but she did not release his name. She said he used a shotgun and had a handgun and several rounds of ammunition.

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As investigators interviewed 100 to 200 witnesses, people left candles and flowers at two memorials outside the mall for the victims.

Many people forced to leave their cars overnight returned Tuesday to pick them up and reflect on what happened.

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"I've worked here for 28 years. It's been the safest place to be," said Steve Farr, who saw pools of blood and broken glass throughout the mall when he was allowed in to check his jewelry store.

Marie Smith, 23, a Bath & Body Works store manager, said she had seen the gunman through the store window. She watched as he raised his gun and fired at a young woman approaching him from behind.

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"His expression stayed totally calm. He didn't seem upset, or like he was on a rampage," said Smith, who crawled to an employee restroom to hide with others. He looked like "an average Joe," she said.

Killed in the attack were two 28-year-old women, a 52-year-old man, a 24-year-old man and a 15-year-old girl, Snyder said. Four people were hospitalized — a man and a woman in critical condition and two men in serious condition, Snyder said.

For hours after the rampage, police searched stores for scared, shocked shoppers and employees who were hunkered down awaiting a safe escort.

Matt Lund was visiting his wife, Barbara, manager of the Secret Garden children's clothing store, when he heard the first shots. The couple and three others hid in a storage room for about 40 minutes, isolated but still able to hear the violence.

"We heard them say, 'Police! Drop your weapon!' Then we heard shotgun fire. Then there was a barrage of gunfire," said Lund, 44. "It was hard to believe."

Witnesses said officers treated everyone like suspects — ordering those hiding in storerooms, bathrooms or under stairwells, to lie on the floor with their hands on their heads until police were sure no one posed a threat.

On the way out, Lund said, he saw a woman's body face-down at the entrance to the Pottery Barn Kids store and a man's body on the floor in the mall's east-west corridor. "There were a lot of blown-out store windows and shotgun shell casings all over the floor," Lund said. "It was quite surreal."

The victims were found throughout the 239,000-square-foot (21,510-square-meter) shopping mall.

Outside, streets were blocked as police swarmed the four-block scene. Dozens of people lingered on the sidewalk, many wrapped in blankets, as they talked about what they had seen inside.

The two-story mall, southeast of downtown, is a refurbished trolley barn built in 1908, with a series of winding hallways, brick floors, wrought-iron balconies and about 80 stores, including high-end retailers such as Williams-Sonoma and restaurants such as the Hard Rock Cafe.

Antiques store owner Barrett Dodds, 29, said he saw a man in a trench coat exchanging gunfire with a police officer outside a card store. The gunman, he said, was backed into a children's clothing store.

"I saw the shooter go down," said Dodds, who watched from the second floor.

Four police officers — one an off-duty officer from Ogden and three Salt Lake City officers — were involved in the shootout with the gunman, Snyder said. She provided no other details.

Barb McKeown, 60, of Washington, D.C., was in another antiques shop when two frantic women ran in and reported gunshots.

"Then we heard shot after shot after shot — loud, loud, loud," said McKeown, saying she heard about 20. She and three other people hid under a staircase until it was safe to leave.

The mall was purchased in August by Scanlan Kemper Bard Cos. of Portland, Oregon, from Simon Property Group for $38.6 million. The company said it planned to invest $80 million, attract a new anchor tenant and possibly add condominiums.

"We are devastated and shocked by this senseless, random act of violence and tragedy at Trolley Square, owner Tom Bard said in a statement posted on the KSL-TV Web site. "At this time our greatest concern and prayers are with the victims, their families and loved ones."

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