(KNOXVILLE, Tenn.) -- A fourth child has died after a pair of separate electrocution incidents at lakes in Missouri and Tennessee.
Nathan Lynam, 11, died Thursday night at Children's Hospital in Knoxville, Tenn., authorities said.
On Wednesday afternoon, Noah Winstead, 10, Lynam's swimming companion at Cherokee Lake outside Knoxville, died after the two boys were electrocuted, possibly by a faulty houseboat electrical cord.
Two other children swimming in another lake, this one in Missouri, also were electrocuted on Wednesday.
Alexandra Anderson, 13, and her brother Brayden, 8, were killed while swimming near a private dock in the Lake of the Ozarks around noon, a couple of hours before the Tennessee incident.
Adults standing on a dock heard screaming and jumped in. Police say those who jumped in felt electricity and cut off power to the dock. The adults immediately began CPR, but it was too late.
Sgt. Paul Reinsch of the Missouri State Highway Patrol said the electricity could have come from any number of sources.
"Obviously, the lights, lots of times, they have slides and they have pumps that pump water onto those slides so the children can use them," Reinsch said. "There's a lot of reasons electricity is on that dock."
Two hours later, the other two boys were shocked at Cherokee Lake outside Knoxville.
"Someone started hollering, 'The kids are getting electrocuted,'" witness Betty Hamilton said.
Other witnesses said the boys had been swimming from one house boat to another when they suddenly cried for help.
"We believe that somehow or another, the electricity at this point got into the metal of the boat, and when the children touched the metal ladder to get in, that's when the electrocution occurred," Grangier County Sheriff Scott Layel said.
Police said seven other people were also injured by the electricity in Cherokee Lake -- four adults and three children -- and were taken to area hospitals for medical attention.
Police in Missouri and Tennessee said they were still unsure what energized the lakes.
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