FBI joins investigation into attack on North Carolina power grid

About 40,000 residents without power on Saturday night after two stations were struck with gunfire

The FBI is joining an investigation into what officials are calling a targeted" attack on a North Carolina power grid that left about 40,000 residents without power on Saturday night.

Rumors on social media suggest that the attack was carried out to stop a local drag show. But officials have said a motive for the attack is unknown.