The first robbery was reported at about 7:30 p.m. Friday near the intersection of 14th Street and Broadway, police said.
The suspect took the victim's wallet and cell phone, police said. The second robbery was reported at about 10 p.m. near the intersection of East 15th Street and 12th Avenue, according to police. The victim suffered minor injuries during the robbery.
A third strong-arm robbery was reported at about 12:25 a.m. today in the 300 block of Lakeshore Avenue, according to police.
No arrests have been made and no injuries were reported in any of the robberies, police said. No suspect information was immediately available, and the robberies are not believed to be related, police said.