CANTON, Ohio (AP) _ A 10-year-old boy who climbed into an electrical substation through a hole in a fence was shocked by a transformer and suffered third-degree burns on more than 80 percent of his body, fire officials said.

Larez Alexander was in critical condition Wednesday at Akron Children's Hospital, a nursing supervisor said.

Customers up to a mile and a half away briefly lost electricity after Tuesday's incident, which set the boy's clothes ablaze, fire department Battalion Chief John Whitlatch said.

Nearby residents heard the explosion, ran outside and saw the boy on fire, Whitlatch said. One man climbed over the fence and removed the burning clothes from the boy, who was trying to get back to the other side, he said.

Two of the boy's brothers were outside the American Electric Power substation at the time. Whitlatch said Larez may have climbed onto the 69,000-volt transformer out of curiosity.

All AEP substations are surrounded by fences topped with barbed wire and are locked and secured, spokeswoman Shelly DiMattio said. The company is investigating the incident, she said.