Three people suffered injuries in an explosion and fire at a building on Merivale Road in Ottawa's south end Thursday afternoon.

Ottawa police, the Ministry of Labour and the Ontario Fire Marshal's Office are investigating the fire in a building at the Eastway Tank at 1995 Merivale Road, south of Slack Road. An Ottawa Fire Service investigator is also part of the investigation into the cause of the fire and explosion.

On Thursday evening, police asked all employees and families to attend a reunification centre at the Woodvale Pentecostal Church on Greenbank Road, "to ensure everyone who was working at this location is accounted for."

Emergency crews are continuing to monitor the rubble of the building for flare-ups, "and search the facility/site", said police.

Nepean MPP and cabinet minister Lisa MacLeod said on Twitter, "My thoughts are with those who were injured and who are missing in the explosion, as well as the families of those affected and the first responders."

Flames and black smoke could be seen coming from the building on Merivale Road at approximately 1:30 p.m. Thursday. Ottawa Fire officials say 911 callers reported hearing an explosion before seeing 50-foot flames shooting through the roof of a structure.

Coun. Tim Tierney says he was visiting a city of Ottawa facility metres away from the building when the fire started.

"I actually thought it was an earthquake at first. The ground was shaking and then suddenly, seconds later, suddenly I hear the bang," said Tierney on Newstalk 580 CFRA's Ottawa Now with Kristy Cameron.

Swapan Sarker was working nearby when he heard three loud bangs.

"So I get out from the warehouse, suddenly I see the fire."

Ottawa Fire Service Acting Chief Paul Hutt told reporters 911 received multiple calls for a fire at a commercial building on Merivale Road.

"Reports were there were heavy flame and smoke coming from this building," said Hutt Thursday afternoon.

Hutt said firefighters declared a third alarm, meaning 30 to 40 resources within the service deployed to the scene.

"Crews arrived on location quickly attempting to suppress the fire, but determined the fire load and the fire conditions were as such they had to go to a defensive attack," said Hutt.

Three people in the building at the time of the fire have been transported to hospital. Paramedics say two people arrived in hospital in critical condition, while the other patient is in stable condition.

Ottawa fire said Thursday evening one firefighter was treated for minor injuries.

Ottawa fire brought in heavy equipment Thursday evening to help suppress the fire.

"As we suppress the fire, there is water runoff that is occurring as a result of us putting water onto the fire. I want to assure residents there is no concern – we have our HAZMAT team on location," said Hutt in an update at 4:30 p.m.

"We're navigating and mitigating any risk. We're sucking up the water that is running off."

Hutt says Ottawa fire is doing air quality monitoring at the fire scene, and there is no concern for residents in the area and no need to evacuate.

Mayor Jim Watson said on Twitter there was a "serious situation" following an explosion at Eastway Tank on Merivale Road.

"My immediate concern is for those employees who've been affected by this fire," said Watson.

According to the company's website, Eastway Tank, Pump & Meter Ltd. Is a custom manufacturer of tank trucks for both the North American and International markets.

 

"I HEAR A LOUD BANG"

Sarker says his two roommates work at Eastway Tank.

"They are doing welding and painting the truck," said Sarker. "There is a lot of hazardous chemicals and tanks."

Witnesses reported hearing a loud "bang" before the fire started.

"I was serving a customer, just finishing up with her and I hear a loud bang. Next thing I know there’s a very large cloud of black smoke," said Jesse Headland, who works at the Francis Gas Bar.

"It’s coming up 'yay high' and eventually I do see some flames hiding behind the truck. Probably the biggest thing I’ve seen in my nine years working here."

Amanda Fung is the owner of the Country Place Chinese Restaurant near the scene of the fire.

"I’m sitting eating my lunch and I smell smoke. When I went out to look at the window outside I saw lots of big flames."

Leonardo De Socio said it was "a little bit shocking" to see the flames so close to his house.

Ottawa police say the Ministry of Labour and the Ministry of Environment have been notified about the fire. 

Merivale Road remained closed Thursday evening between West Hunt Club and Macfarlane Road. Slack Road is closed eastbound at Woodroffe.

FAMILY REUNIFICATION CENTRE

A family reunification centre has been set up at Woodvale Pentecostal Church on Greenbank Road.

Ottawa fire says the purpose is to reunite employees with their families.

With files from CTV News Ottawa's Jackie Perez and Tyler Fleming