The city of Winston-Salem released an urgent alert Wednesday night after a house fire was linked to a kerosene and gasoline mix-up at a local convenience store. Anyone who purchased what they believed was kerosene from the Akron Market Citgo station, located at 3890 Glenn Ave., in the past 10 days should not use it, authorities said. Gasoline has the potential to explode if used in a kerosene heater. Division Chief Jeff Heitman of the Winston-Salem Fire Department said that firefighters became aware of the problem when they responded at 6:30 p.m. to a house fire on Doris Street in the city’s northeastern section.