Firefighters say a four-acre brush fire that ignited above a neighborhood on Saturday was sparked by a metal grinder. The Cordial Fire broke out at about on a hillside near Cordial Road and Avenida Del Charro just before 4 p.m. The fire originally began with moderate rate of spread before crews quickly stamped it out and prevented flames from threatening structures. Firefighters said the fire began after a metal grinder sparked dry grass. "A small mishap can have disastrous effects, especially this time of year. Please be fire safe in everything you do," a tweet from CAL FIRE San Diego said. A fire crew was set to stay on scene into the evening to mop up the area.