turning deadly. at big bend national park, officials say a 14-year-old boy died after passing out while hiking in 119-degree heat. the boy s stepfather racing to get help, was tragically killed in a car crash, according to the national park service. both deaths are under investigation. we have multiple patients. reporter: and in houston, a dozen people trying to cool off from the brutal heat were rushed to the hospital saturday after getting sick at a lazy river pool from possible chlorine poisoning. there are several children having trouble breathing, pool ingested chlorine. reporter: the pool authority declining to comment. now with more blistering heaton way, the texas power grid is being pushed to its limits. its operator, ercot, issuing a weather watch all the way through friday, bracing for record-breaking demand. as people try to beat the heat any way they can.