A female victim reported a male attempted to take her cellphone from her on a Fremont bound train at the San Leandro Station, at 1126 hours. The suspect was described as a Black male, tall, thin, wearing a gray hoodie with black hood and sleeves. The victim held onto her cell phone and the suspect fled. At 1329 hours, an officer spotted a male who matched the given description of the earlier theft and detained. The suspect was identified as a juvenile and a records check showed he was a runaway. The male was taken into custody and officers located a firearm in his possession. The male was placed under arrest for the firearm violation.