The two-alarm blaze broke out at Burton Brothers Hardware Monday night.
Seaford Volunteer Fire Department Chief Mark O'Bier says firefighters had to evacuate at one point.
"The roof of the structure is partially collapsed, about half of the building is caved in. It's a 100+ year old, probably 150-year-old building or so. It's on the national historic registry," says O'Bier.
The landmark sustained significant fire and water damage.
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