(CBS) — One man was killed, and two other people were wounded, including a 12-year-old boy, when a gunman opened fire inside a Starbucks in the Uptown neighborhood after a drug deal, police said.

Around 8:15 p.m., the shooter chased a man into the Starbucks at Wilson and Broadway, after a drug transaction a few blocks away, according to Town Hall District Cmdr. Marc Buslik.

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Witnesses said the gunman, who was wearing a ski mask, opened fire inside the store.

The man he was chasing was shot and killed. Sauvignon Watkins, 28, was pronounced dead at the scene.

A 24-year-old man was shot in the abdomen, and a 12-year-old boy was shot in the groin. Police said Watkins and the 24-year old knew each other. They are both gang members and were involved in the drug deal.

The 12-year-old boy was not connected to the others involved and was just an innocent bystander, police told CBS 2. He was doing homework at the Starbucks when he was shot in the groin.

Mike Swaiko was entering a bar nearby when he heard the gunfire.

“Heard two shots, grabbed my wife, pushed her down, and the bartender opened the door to the bar and said ‘everybody get inside,’ and I heard three more shots. I was looking over my shoulder, and just saw a young person, or whatever person running out wearing a ski mask,” he said.

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The 12-year-old boy was taken to Lurie Children’s Hospital. He was in good condition Friday morning, police said.

The 24-year-old man was taken to Advocate Illinois Masonic Medical Center. He was in serious condition.

Starbucks said it is cooperating with the investigation.

“We were saddened to learn of the passing of a young man and the injury of two others as a result of gun violence at our store on North Broadway in Chicago. The store will be closed tomorrow morning as we focus on our local store partners, ensuring they have the support they need,” the company said in a statement Thursday night.

Alderman James Cappelman, whose office is just down the street from the incident, called the act “senseless violence.”

Watkins had two misdemeanor offenses on his record, including child endangerment from August of this year. Police said a weapon and drugs were found on him.

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No one was in custody Friday morning. Area North detectives are investigating and looking at surveillance video.