Ten people were arrested in the downtown shooting, and nine firearms were found, according to Milwaukee Police Chief Warren Allen.
Allen said 17 people were shot, ranging in age from 15 to 47.
He said that all casualties in both shootings were expected to survive.
In a video taken by someone at the downtown shooting scene, multiple shots and screaming owners can be heard.
“We were waiting for the Lyft, and we walked through this intersection like three minutes before, and we knew something was wrong, so we ordered her to take us down the road,” the person who filmed the video told CNN.
“The people in the middle of the street were loud and obnoxious,” he added. “People are yelling at each other back and forth.”
In the shooting near the arena, two men, 26 and 29, and a 16-year-old girl were injured, according to Allen.
“A 19-year-old man has been detained in connection with this incident,” Allen said. “Fees pending review by the Milwaukee County District Attorney’s Office.”
This incident occurred at approximately 9:12 p.m. near the intersection of Martin Luther King Jr. and Highland Avenue, around a block of Bucks Main Courthouse at the Fiserv Forum.
The police did not release the names of the people involved nor a possible motive.
The Bucks lost to the Boston Celtics on Friday night – 108-95 – forcing a seventh game on Sunday to determine who would play the Miami Heat in the Eastern Conference Finals.
CNN’s Lichil Behnken and Sarah Smart contributed to this report.