A 20-year-old man was pulled over and jailed after a traffic violation. He died later that day in police custody

Milwaukee Police Chief Jeffrey Norman said an independent investigation into the death is underway.

(CNN)Three Milwaukee police officers have been suspended after a man arrested during a traffic stop Wednesday died in jail hours after he was taken into custody, Milwaukee police said.

Keishon Thomas, 20, was pulled over for a traffic violation around 1:55 a.m. Wednesday, police said. He was arrested on an outstanding warrant and had "suspected illegal narcotics," Milwaukee Police Chief Jeffrey Norman said.
Details of the warrant were not immediately available.
      About 16 hours after the traffic stop -- around 5:53 p.m. -- the man was found to be in medical distress during a routine cell check at the Milwaukee Police District 5 office, Norman said. Officers provided lifesaving measures until they were relieved by the Milwaukee Fire Department, police said in a news release.
        The man was later pronounced dead.
          Norman said Friday the officers were suspended with pay.
          The chief said he had concerns about the incident, but did not elaborate.
          "As we are going through this process, we are finding things that, you know, need some more further explanation in regards to what happened," he said.
          Police spokesman Sgt. Efrain Cornejo did not elaborate on the reason for the suspensions.
          Thomas' death comes amid heightened scrutiny of cases in which people die or are injured in police custody.
          The incident is being investigated independently by the Waukesha Police Department, according to the Milwaukee Police Department. The officers involved have not been named.
          Plans for a community briefing to discuss the incident are forthcoming, police said.
          Friday, at the same police station, a 23-year-old suspect was shot by officers after he allegedly opened fire inside the building, Norman said at a press conference.
          The man "fired several shots at the MPD staff," Norman said. "At the time, there were several community members inside the lobby." The chief said the suspect fled after one officer opened fire on him, and officers chased him.
          "During the encounter, multiple officers discharged their weapons," said Norman. "The suspect was struck multiple times." The chief described the suspect's wounds as "nonfatal," and no one else was hurt. The suspect was not named.
            Chief Norman would not speculate on whether the shooting had any connection to Thomas' death Wednesday.
            An independent investigation into the Friday shooting will be conducted by the West Allis Police Department.