Savannah-Chatham police are investigating three robberies occurring on Oglethorpe Avenue on Thursday between 9:09 p.m. and midnight. One of the robberies resulted in an arrest, and another resulted in an injury, said Eunicia Baker, Savannah-Chatham police spokeswoman. At 9:07 p.m. Thursday metro responded to an armed robbery reported on the 200 block of West Oglethorpe Avenue.