MASON CITY — Police for the second time in a month are investigating an incident where shots were allegedly fired in Mason City. The Mason City Police Department says shortly before noon this past Saturday, officers responded to the alley east of the 300 block of North Monroe on the report of possible gunfire. None of the people involved in the shooting were at the scene when officers arrived. Officers did find shell casings from two different firearms in the alley. Police Lt. Rich Jensen says two search warrants have been served during the investigation but no arrests have been made. Jensen says the investigation is still active and anybody with information should contact the Police Department at 421-3636.