TAMPA — A 15-year-old boy was fatally injured Friday evening after being struck by an undercover sheriff’s vehicle, according to the Hillsborough County Sheriff’s Office.The incident took place at about 6:30 p.m. on N Florida Avenue near E 124th Avenue, sheriff’s officials said.The deputy, who was working undercover, was driving north on Florida Avenue and had the green light to cross the intersection of E 124th Avenue.The deputy saw a teen walking a bike across Florida Avenue, officials said, and swerved to avoid him. But the sheriff’s vehicle ended up striking another teen.The injured teen did not survive, officials said. His identity was not released by the Sheriff’s Office on Friday night.The teens were crossing the road north of the crosswalk, officials said. An investigation into the incident is underway and the Sheriff’s Office said it needs to determine how fast the deputy was going at the time.Family who came to the scene of the crash believed the deputy had driven off after the incident, officials said. But the deputy had returned to the scene. Officials said the family did not realize that because the deputy was not driving a marked sheriff’s vehicle.The identity of the deputy involved in the incident was not released by the Sheriff’s Office. The agency said he has been employed there for five years and 10 months.