HOUSTON (AP) — Investigators say a science experiment that flared into a flash fire at a Houston-area preschool and left a dozen children hurt involved methanol and chemical salts.

The experiment went wrong Tuesday outside the Yellow School in Bunker Hill Village.

Village Fire Chief David Foster said Wednesday that a teacher poured an accelerant onto chemical salts in bowls, part of a reaction creating different colors. Officials say the teacher apparently didn't notice a flame was already in one of the bowls, leading to the fiery accident.

Officials say six children were transported to a hospital for treatment of minor burns, while six others required lesser medical attention — including one child trampled while fleeing.

Foster says several other teachers were present during the accident.

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