No humans have been harmed in the fire.
State Fire and Rescue service (VUGD) said the call was received at 2:43 at night.
The building is burning throughout its entire area of 13 500 square meters. Fire containment works are ongoing.
Several walls have collapsed, said VUGD.
Humans have not been harmed but pets and birds in the store have likely been victims to the fire. No official confirmation on that has yet been received. Ceilings and walls have caved in. There is a chance the building might collapse.
Residents of adjacent houses were evacuated. They were later allowed to return but many are afraid to do so. Paints, lacquer and other chemicals are burning so Rēzekne residents near Stacijas street are asked to refrain from opening windows.
Traffic has been suspended, said VUGD.