The fire chief says the dock lines securing that boat burned off, and the burning vessel then drifted and caused another boat and two docks to catch fire.

The man, his 16-year-old son and a friend, 15, were at the boat launch near Highland Road and Williams Lake Road, preparing to take a 17-foot Chris-Craft boat onto Pontiac Lake when the explosion happened.

Officials say the 17-foot Chris-Craft boat exploded after the ignition switch was turned on, injuring the Waterford father (45), his son (16) and their friend (16). The friend was transported to an area hospital with burns over 50 percent of his body. He was last listed in critical condition.