NEW YORK (AP) — Electric utility Con Edison is working to figure out what caused a high-voltage equipment failure that unleashed an otherworldly flash of bright blue light in the night sky over New York City.

The event Thursday night filled social media feeds with eerie photos, questions and jokes, to the point that even the New York Police Department tweeted there was “no evidence of extraterrestrial activity.”

While Con Ed initially described a “brief electrical fire” at a power substation in Queens, spokesman Bob McGee says Friday that what happened was what’s called an “arc flash” — somewhat like a bolt of lightning — after a malfunction in equipment that carries 138,000 volts of electricity 20 feet (6 meters) up in the air.

He says the flash subsided on its own.