Lac-Mégantic resident Adrien Aubert filmed the tanker train explosion in his Quebec community early Sunday morning, and posted the video online.
"All of downtown is on fire," Aubert said in the video as a fireball erupts in the Quebec town of 6,000 people.
Aubert was about 200 metres from the explosion, which destroyed much of the town's core.
In an interview with Radio-Canada, Aubert said at the time he was on his way to Musi-Café, a popular bar at the epicentre of the explosion.
"If I had, I wouldn't have the chance to be a witness and be speaking today," he said.
Aubert said he didn't know what was happening at first, thinking it could have been fireworks.
"It was a mix of people who were panicking, but also a lot of people who were standing there open-mouthed without really reacting, because I think it's not something they are used to seeing in this part of the world," he said.
Aubert said he knows many of the people who are still missing.
"It's a town where everyone knows each other. Unfortunately, like everyone, I know people who have disappeared," said Aubert.