SAUGUS – Firefighters moved quickly to extinguish a fire at 276 Central St. Monday afternoon that forced a mother and her 5-year-old son to flee the residence.Fire investigators are working to determine the cause of the fire, but Fire Chief James Blanchard said renter Lisa Beiras and her son Stephen were not hurt in the blaze. Blanchard said a Lynn firefighter suffered an eye injury fighting the fire and was taken to the hospital.Beiras’ husband, also named Stephen, and four other children were not at home when the fire started in a second floor bedroom at 12:40 p.m.Lisa Beiras was in the home’s first floor when her son ran downstairs.”She suspected something was amiss, asked him what was wrong and then ran upstairs,” Blanchard said, adding the boy hid in a first floor bathroom but was promptly discovered.”If he had hid in the upstairs bathroom, he would have been dead.”Saugus Engine 1 and Ladder 1 responded to the fire. Blanchard said Engine 3 would have probably been the first truck to reach the fire but the engine and its crew were on another call when the fire broke out.Wakefield and Lynn firefighters also responded to help town firefighters extinguish the fire by 2:15 p.m. Blanchard lives near 276 Central and was eating lunch at home when the fire started.”Fire was coming from the second floor when I got there. The guys did a remarkable job putting it out.”The residence is owned by St. John’s Episcopal Church and was once the parson’s residence. Blanchard said the church maintains the house as a rental property. The Red Cross helped the Beirases find temporary shelter in a local hotel.