The incident occurred when the pilot was trying to land the balloon in a hay field Saturday night in New Holland in central Pennsylvania.
Its top got caught up on the power lines as it was deflating, said Sergent Mark Willwerth of the New Holland Police Department.
"There does not appear to be anything wrong with the balloon, and weather is not believed to be a factor," he was quoted as saying by CNN.
All three people aboard were hospitalised at a local trauma center with severe injuries.
Police did not release their identities, the report said.