Volunteer firefighters were summoned at about 9:15 p.m. yesterday to a garage fire on North Spruce Street in Summit Hill. A can containing sawdust began burning hours after hamburger grease was apparently discarded in it, according to officials. Summit Hill Fire Chief Shawn Hoben said the fire was contained to the can and was quickly extinguished, although heavy smoke filled the concrete garage. There were no reported injuries. Responding were firefighters from Lansford and Summit Hill. Also at the scene were police officers from Summit Hill and Lansford and the Lehighton Ambulance Corps. Fire police handled traffic control. Hoben ruled the cause accidental. The garage is owned by Paul McArdle Jr.