To me, with the circumstantial evidence of a power outage, it looked like an electrical arc.
An electric arc can be seen for many miles. An arc is also very hot. I’ve seen evidence of an arc setting green grass ablaze at a distance of at lease 100 feet.
It can also cause a sunburn like effect on unprotected skin. However, most of the guys I worked with in the electrical industry, ran like hell, so that effect was not a problem.