Petaluma fire officials are investigating the cause of an early morning house fire in east Petaluma that forced four residents from their home. According to the Petaluma Argus-Courier, crews responded just before 2 a.m. Friday to a single-family residence in the 2000 block of Knight Avenue after reports of smoke rising from the roof and attic. Firefighters arrived within five minutes and successfully contained the flames, protecting neighboring …