3 children electrocuted while swimming in lakes; 3 drown in river Saul Young / AP Evidence tape covers an electrical meter near two houseboats at German Creek Marina on Cherokee Lake in Bean Station, Tenn., on Wednesday. One boy died and another was critically injured after an apparent electrocution. Updated at 8:40 p.m.: Three children died -- two in Missouri and one in Tennessee -- after they were shocked by electricity while swimming in lakes, authorities said. In another tragedy, three children drowned in the Iowa River, police said. In Missouri, 13-year-old Alexandra Anderson and her 8-year-old brother Brayden of Ashland were killed when they were shocked around noon by an unknown source of electricity while swimming near a private dock in the Lake of the Ozarks, KSHB-TV reported. The Missouri Highway Patrol said investigators were looking at electricity powering lights and a pump that supplies water to a slide children use at the dock, but they had not determined what had caused the electrocution by Wednesday evening. The scene at German Creek Marina on Cherokee Lake in Bean Station, Tenn., on Wednesday after a boy died and another was critically injured in an apparent electrocution. Both boys, whose names were not released, were originally reported dead but Sheriff Scott Layel said one child was revived on a medical helicopter flight. The sheriff's department said several other people were taken to the hospital in Morristown to be checked out because bystanders trying to rescue the boys were shocked as well. Layel told the Knoxville News Sentinel that wiring in the bottom of one of the houseboats might be the issue behind the shocks. It was uncertain whether the boys were shocked in the water or when they touched the metal ladder of one of the houseboats, Layel said. Drowning claims three other children In another incident, the bodies of three children were found in the Iowa River Wednesday night near Marshalltown, NBC station WHO of Des Moines reported. The station said the children were reported missing around 6:30 p.m. and the bodies of two girls and one boy, ages 6-10, were found just before 9 p.m. Police say the children were swimming in the river.