TULSA, Okla. -- Tulsa police on Thursday arrested a man accused of gunning down a rival outside an electronics store and mistakenly killing an innocent bystander who was shopping with his daughter.

Police Chief Chuck Jordan announced that police arrested 20-year-old Willie Wise in Saturday's slayings at a Best Buy store in Tulsa's midtown. Police allege Wise fatally shot 34-year-old Scott Norman multiple times in what was believed to be a gang-related crime. One of the bullets struck 58-year-old Graydon Brown, who was inside the store, shopping for DVDs with his daughter, according to police.

Wise was booked into the Tulsa County Jail on two counts of first-degree murder shortly before noon Thursday, according to jail records. He is being held without bond. No attorney was listed for him in jail records.

Police said Norman's killing was possibly in retaliation for other homicides. The dispute between Norman and Wise dated back to 2008, Jordan said. The two men happened to run into each other at a local shopping mall Saturday, and Wise followed Norman to the Best Buy, Jordan said.

At a police conference Thursday morning, Jordan said the brazen killings "shocked the conscience of everybody in the police department, and certainly everyone in the community."

Police allege someone else was driving the car that stopped in front of the store so Wise could begin firing on Norman. Jordan said he could not say who the alleged driver was. He said additional details would be turned over to the district attorney's office.

Jordan also announced that a possible accomplice was taken into custody but has not been charged or booked. That person is still being questioned by investigators. A third person was arrested Wednesday in connection with the double shootings, but her role in the crime was unclear Thursday.

Tulsa Mayor Dewey Bartlett, who also spoke at the news conference Thursday morning, said it's important not to forget that someone "had a person violently taken away from their family."

Bartlett also praised the "extremely significant" police work in apprehending the suspects and pledged to the community that local law enforcement will continue to combat gang activity in Tulsa.

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