Lightning struck a tent at the Whitby Ribfest just before 2 p.m. ET, leaving at least 17 people injured.
Colin O’Regan, the chair of the event, said the storm rolled in quickly and the sudden change in conditions was startling.
"Our patrons, they were within a large dining tent that’s on the site, sitting and enjoying their lunch and enjoying the music," O’Regan told CBC News in a telephone interview.
"And obviously, there was a strike to one of the tent poles and has obviously led us to the point where there was 17 people that have been injured."
O’Regan said the injured parties were taken to two area hospitals with non-life threatening injuries.
‘The most painful thing I’ve ever felt’
Bill Sandiford said the rapid change in the weather had prompted many people at the event to squeeze in under the same tent, moments before the lightning strike.
"The tent was absolutely packed full of people," Sandiford told CBC News in a telephone interview.
"It seemed like the rain was just about over and we could see lightning off in the distance."
Sandiford said he went through a few seconds of intense pain when the lightening hit.
'It was so painful, yet the pain was gone so fast. The pain didn’t linger," he said.
"I mean it was just the most intense painful thing I’ve ever felt in my entire life, or that I could ever imagine feeling and then five seconds later, it was just gone."
Durham Regional Police reported receiving a call about the lightning strike at about 1:45 p.m. local time.
Sunday was the last day of the Whitby Ribfest, at the city’s Victoria Fields. The festival was due to wrap up at 7 p.m., but was cancelled after the lightning strike.
Whitby is located about 60 kilometres east of Toronto.