Otherworldly visitors? A wizard calling for help? Demons from the underworld?
A flare from the Imperial Oil's Strathcona refinery set the Edmonton skyline ablaze on Tuesday and lit up social media with theories about the city's possible dystopian fate.
As a column of red vertical light lit up the evening sky, many hypothesized the capital was being invaded by little green men.
"Welcome to Earth, aliens," wrote one apparently awestruck Edmontonian.
In a tweet, Edmonton Fire Rescue Services said it received numerous calls from people concerned about the smoke and flames, but said the flaring was no cause for alarm.
"We have determined this to be the flaring from the Strathcona Refinery which will continue for the next 48 hours," reads the tweet. "Thank you for your diligent reporting, but this is not a fire event."
Flares are used in refineries and petrochemical facilities to safely burn excess hydrocarbon gases that can't be recovered or recycled.
Even so, Edmontonians took to social media to share ominous photographs and hypothesize that something else was afoot.