NORWALK - Firefighters say a live-in nanny and a baby safely escaped a Norwalk house fire last night because of an emergency plan they practice every month.Officials say a live-in nanny was at 8 Rockridge Drive with a baby when she noticed the outdoor patio was engulfed in flames. She and the baby ran to a neighbor's house, safely escaping the fire. Firefighters say it's best to have a plan in place in the event of a worst-case scenario.Authorities believe a cigarette left in an ashtray outside the house caused the fire.Meanwhile, a new state law kicks in on Oct. 1 that will require a smoke detector in every residential property.