A vacant residence in Wilmington took heavy fire damage during an early-morning incident Monday. Wilmington firefighters were dispatched around 1:15 a.m. to a residential structure fire at 608 E. 11th St. When they arrived, crews found smoke coming from the roof and rear of the row home. The adjoining home at 610 E. 11th St. also was damaged by the fire. It was a four-hour operation to knock down the fire, but there were no reports of injuries. The Wilmington Fire Marshal's Office is investigating its cause. Around 30 fire and EMS personnel responded to the fire, including the following units: Skyboom 2; Squad 3; Squad 4; Tower 1; Engine 1; Engine 5; Ladder 2; Battalion-1; Battalion-2; FM-14; St. Francis EMS; New Castle County Medics; and Wilmington Licenses and Inspections.