WINONA — Investigators are focusing an electrical cause of the historic fire that consumed several buildings in downtown Winona.

Deputy Police Chief Tom Williams said Tuesday the most significant burn and char marks are near an electrical conduit in the building where the fire apparently started — the Islamic Center of Winona.

He says federal, state and local investigators plan to dig through the rubble at the former Islamic Center again next week. A similar effort was done last Saturday by about ten investigators. Williams says heavy equipment, such as a crane, is too costly, that’s why investigators are digging by hand.

The fire last Friday destroyed three buildings, including the Islamic Center.