Beloit fire officials are urging residents to never leave a cooking grill unattended.  Firefighters were called to a home in the 1100 block of Highland Avenue a little before 3:30 p.m. Sunday for a residential fire.  Officials say the fire was started by an unattended cooking grill located on the back porch and spread aggressively due to the windy conditions and low humidity.  Two people were home at the time of the fire, but safely escaped.  The home was heavily damaged.