SAINT JOHN, N.B. -- First, Jonathan Wright heard a loud hissing.

Then he was thrown to the ground and turned to see a wall of orange, as flames surrounded him and several other workers after a massive explosion at the Irving Oil refinery in Saint John, N.B., on Monday morning.

The American contractor said his workspace was approximately 35 metres from the blast -- and the only stairway out was blocked by flames.

"You could not see anything besides smoke and flames," Wright said. "I thought we were done right there."

Wright told his story Tuesday, as the refinery regrouped from the Thanksgiving Day explosion which shook the historic port city shortly after 10 a.m. local time and injured at least four workers.

Mayor Don Darling said Tuesday residents living near the refinery remain "very nervous," even though the fiery incident has been stabilized. He said the city's large industrial base comes with risks and there needs to be a broader discussion about the interaction between residents and industry.

The Saint John Emergency Measures Organization said Tuesday it has been "deactivated," although some firefighters remain on the scene as recovery efforts continue. The last flare up came at 9 p.m. Monday, "as part of the normal stabilization process," the EMO said.

At the time of the explosion, there were as many as 3,000 workers on the site.

Wright, 43, an electronics technician from Florida, said he's worked at refineries around the world for 11 years, but has never experienced anything like Monday's drama.

"It was a (expletive) nightmare, I've never seen anything like that in my entire life," Wright said in an interview on Tuesday.

"I thought I was dead for sure."

Wright said he had to jump through high scaffolding and pipes several metres in the air to escape. He didn't realize his coworkers were behind him until after he was outside, and he thought they were likely killed.

Once he got outside, Wright left the premises after getting a ride with someone else who was about to pull out of the parking lot.

The Floridian said he feels lucky to have escaped, and lucky that neither he or his coworkers were severely burned. He said he pulled muscles and sustained scrapes and cuts in the clamber to escape.

"It was just a blur getting out of there. I just never imagined jumping through all that stuff, pipes and scaffolding and stuff. I just never thought that would happen to me, but you know, it did. I just can't believe we weren't burned."

Wright is flying home to Florida Wednesday, and said most of all, he is looking forward to hugging his kids and his fiancee when he lands.

Irving Oil tweeted on Tuesday that the site of the incident is "isolated and contained," and said workers will be back to work on Tuesday evening.

Eric Brideau, assistant director of investigations with WorkSafe NB, said Tuesday the investigation will focus on occupational health and safety issues.

"We want to find the cause to make sure it doesn't occur again … We can write orders or it can go all the way to a prosecution, that's just a potential," Brideau said.

"A refinery is a very complex piece of equipment and Irving as a contractor and owner of the business, they obviously have a very large responsibility to ensure the health and safety."

Darling called the city's emergency response to the explosion "fantastic," but said the city needs to ensure it has proper plans in place to protect residents. He said there will still be an extensive review of the city's handling of the incident, including its communication with residents.

"We live in a world of almost instantaneous communication ... so I think communications need to be reviewed -- and I think the relationship that we have with our industrial partners in our city needs to be reviewed as well," he said, noting there have been other industrial accidents in the city.

"We have a very, very high concentration of industry here in Saint John and I think we've gone through a series of butane leaks and explosions and fires and I think it has people very nervous and rightly so -- we have to have that broader discussion about the interactions and interface between the city and the industrial players in our city."

An Irving official told reporters Monday there had been a malfunction in the refinery's diesel treating unit, where sulphur is removed from diesel fuel.

Irving's website says the refinery produces more than 320,000 barrels of "finished energy products" every day.

Patrick Stull, director of the Saint John regional office of the Department of Environment and Local Government, said they found no signs of air quality "exceedances" during the fire.

"What will happen now is obviously our staff will continue to meet with the refinery and will continue to monitor the situation and will also have a detailed incident report provided from the refinery as well," said Stull.

- By Holly McKenzie-Sutter in St. John's, N.L., and Brett Bundale in Halifax.