The Milwaukee Journal Sentinel reports Mayor Tom Barrett announced the change Sunday following a violent weekend. He didn't specify how many more officers would be present on patrols.
He says he met with Police Chief Edward Flynn on Friday to discuss the department's tactics.
At least 12 people have been shot in the city since Thursday. Three of those shootings were fatal.
Barrett says there were 33 homicides last year during August and September. There were 105 total in 2013.