The suspected shooter, 26-year-old Jordan Fricke, was arrested without incident, according to a statement from Milwaukee police.
Rittner is the third Milwaukee police officer to be killed in the line of duty in the last eight months. Officer Charles Irvine was killed June 7 when he was in a crash and his squad car rolled; Officer Michael Michalski died July 25 after being shot while trying to make an arrest, WISN-TV reported.
“This has been an incredibly difficult year for the department — now the third officer that has lost his life in the service of Milwaukee. So it’s a sad day for this community,” Milwaukee Alderman Bob Donovan told media outlets.
Rittner was a U.S. Marine and served two tours of duty in Iraq, the Milwaukee Journal Sentinel reported.
He began his career with the Milwaukee Police Department in 2001 at the age of 17 as a police aide. Rittner rose through the ranks and became part of the Tactical Enforcement Unit. Police records show he was awarded the medal of valor for helping to free hostages from a gunman in 2015.
Rittner was married and had a young child, according to the Milwaukee police statement.