The Marywilska 44 with almost 1,400 commercial units - including many kiosks - was among the biggest shopping centres in Warsaw, Reuters reported.
It was owned and managed by Mirbud (MRB.WA).
"Almost 100% of it was burned. The fire is being extinguished and this will take many hours, perhaps several hours," Mariusz Feltynowski, commander-in-chief of the State Fire Service told a news conference on Sunday.
He added that almost 200 firefighters were taking part in extinguishing the fire.
SD/PR