FRANKFORD — A structure fire that caused an estimated $500,000 in damage Wednesday was accidentally caused by discarded smoking materials, authorities said.

The blaze, reported shortly before 2:30 p.m., occurred in the 38000 block of Beechwood Court in Bethany Meadows, Delaware State Fire Marshal’s Office spokesman John Galaska said. The Millville Volunteer Fire Co. arrived on the scene and found smoke and flames coming from the middle of a row of town homes. Mutual-aid fire companies assisted at the incident.

The town home was occupied at the time of the fire, and a person escaped without injury, Mr. Galaska said.

In total, four town homes were damaged.