The deadliest wildfire in Californian history may have been caused by a single broken steel hook that held up a high-voltage line on a nearly 100-year-old PG&E transmission tower. The Camp Fire, which is known to have killed at least 85 people, began at the base of the aging infrastructure installation. Footage captured by NBC Bay Area News shows loose and trailing wires, as a result of damage to a hook that fractured during high winds on the morning of Nov. 8. “PG&E failed to maintain the tower, and they have an obligation to do that, and it means they are liable for this disaster,’’ said attorney Dario de Ghetaldi, who is suing the utility over the fire. In 2012, five similar towers collapsed during a winter wind storm.