Police from Janesville are investigating a report of shots fired last night. Police looked into the incident on Rockport Road, near Cherry Street after 11PM. A search warrant was executed at approximately 2:30 Monday morning in the 600 block of Rockport Rd. A handgun was recovered and police took Jason Sun into custody for a probation violation. He is being held at the Rock County Jail. There were no reported injuries. The investigation is ongoing and Police are asking anyone with information to contact the Janesville Area Crime Stoppers.