OAKLAND -- Anthony Sheppard stood in disbelief Thursday outside the cellular phone store where its well-known and highly respected owner was gunned down the night before during a robbery.

"I heard about it last night and I didn't want to believe it was him," said Sheppard, 30, as he stood near a small crowd outside the store that had been a fixture in East Oakland since 1996. "I was hoping it wasn't him and I got here and it was. He was a good man. Why they do him like that?"

Wilbur Bartley, 50, was found slain about 7:22 p.m. Wednesday inside Marcus Cellular, 9230 International Blvd., a Metro PCS outlet and Direct TV dealership.

Police said Bartley had named the business after his son and many of his customers and residents who knew him as "Mr. Marcus" were saddened and stunned by his death.

Bartley, who lived a few blocks away, apparently was in the process of closing for the evening when he was confronted by someone who robbed and shot him, police said.

Police would not disclose what was taken.

The killer fled before police arrived.

Sheppard, who said he bought his first pager at the store in the late '90s, expressed sorrow Thursday.

"He was a generous man. I was friends with his son," Sheppard said, his voice cracking. "This shouldn't have happened."

Police said Bartley was a hardworking businessman who was always willing to lend a hand to someone in need and who would give tickets to Oakland Raiders games to children.

Officer Robert Trevino, the lead investigator, said Bartley's death "is a tragic situation, not only for his family but for the community.

"We are doing everything we can to solve this case and we are confident that with the help of the community we can," he said.

Police Chief Howard Jordan dropped by Thursday afternoon to meet with the family, as officers urged residents to share any information that may help solve the crime.

"(There's) a lot of community outrage because this gentleman was so well-respected," Jordan's chief of staff, Sgt. Chris Bolton, wrote in an email. "The chief had met him a few times during walks in that neighborhood this past year."

Oakland police spokeswoman Johnna Watson said motorists are stopping in the street near the store, holding up traffic, to share their disbelief and plead with investigators on the scene to find the shooter.

"This is an outcry from the community I have not seen before," Watson said.

Many who visited Bartley's business to pay their respects appeared either angry or in shock.

About 11:30 a.m., an unidentified man walked past the business, shook his head, then kicked the side of the building and cursed.

"This has got to stop," the man said, then walked away from the closed business where flowers and candles lined the ground.

Just before noon, Patricia Boens, of Oakland, placed a white teddy bear on the ground beside a dozen red roses.

"He didn't deserve this," Boens said. "He was a nice man."

Shortly after, two women hung up a large white piece of paper to create a memorial wall for Bartley.

"RIP Marcus. The community won't be the same without you," one person wrote.

Bartley had been targeted in a robbery before, in January 2007, by someone who apparently followed him home from the store.

But the robbery was foiled outside the residence by Bartley's German shepherd, Buffy, who had been waiting for him and attacked the robber. The robber shot the dog in the leg before fleeing. The 7-year-old dog was treated, but died a month later.

Bartley's killing was the city's 107th homicide of the year.

Police and Crime Stoppers of Oakland are offering up to $15,000 in reward money for information leading to the arrest of the killer. Anyone with information may call police at 510-238-3821 or a tip line at 510-773-2805.

Staff writer Kristin J. Bender contributed to this report.