Heavy smoke from top of CN Tower generates brief panic on Twitter

Heavy smoke was seen atop the CN Tower in Toronto, which was the result of a pyrotechnic display late Thursday. Many onlookers did not know this was a planned event and took to social media with their reactions.

The plume was caused by fireworks in preparation for the Pan Am Games, which are slated to start Friday in the city. Toronto Fire said it was aware of the rehearsal but didn't realize it would create so much smoke.

Not aware of the planned event, many people took pictures of the incident and posted on social media. Some tweeted concern that there was a fire or possibly an explosion at the observation deck of the 1,800-foot concrete tower located in downtown Toronto, Ontario, Canada.