IOWA CITY, Iowa—Authorities are investigating the cause of an accident that killed a boy on a popular boat ride at an Iowa amusement park—the second deadly incident on the ride in five years. The accident happened Saturday night on the Raging River at Adventureland Park in Altoona, Iowa, when a boat carrying six people flipped over. Michael Jaramillo, 11, died Sunday from his injuries, and another minor remains hospitalized in critical condition, the Altoona Police Department said Monday. Two other riders suffered minor injuries. “Our thoughts and prayers are with the Jaramillo family as they navigate the heartbreaking loss of their child,” said police spokeswoman Alyssa Wilson, adding that investigators weren’t sure where the family resides. The ride uses a conveyor belt to move large circular rafts through rapids. After the boat overturned for reasons that remain unclear, emergency responders and witnesses helped to free the riders, and four were …