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.
More than zero people saw how the fire started
( z1 see :ARG0 ( z2 person :quant ( z3 more-than :op 0 ) ) :ARG1 ( z4 thing :manner-of ( z5 start :ARG1 ( z6 fire ) ) ) )