Witnesses told police a gas canister exploded to start the fire in a multilevel building which houses the Ycua Bolanos supermarket, a food court and a parking garage, causing the bottom floor to collapse.
There are people who were interviewed and explained how the fire started
( z1 and :op ( z2 interview :ARG1 ( z3 person ) ) :op ( z4 explain :ARG0 z3 :ARG1 ( z5 thing :manner-of ( z6 start :ARG1 ( z7 fire ) ) ) ) )