HOUSTON, Texas (KTRK) -- Police believe celebratory gunfire overnight could be to blame for a man being shot during a family Christmas party in southwest Houston.Investigators tell Eyewitness News the man was inside a house on Reamer Street and Braeburn Glen Boulevard when a bullet went through the back door, hitting him in the back.Officials are now trying to figure out who fired the stray bullet."We're not sure where it came from outside. Whether it came from a neighbor's house or from the backyard of the complainant's house right now. There were a lot of fireworks going on at the time, so one single gunshot wasn't really noticed," Detective G. Black with the Houston Police Department said.The man was taken to the hospital and is expected to fully recover.