Officials now say 20 people were injured and three were treated in hospital following an explosion in Wheatley.
The blast shook the town's core at the corner of Erie and Talbot Streets around 6 p.m. Thursday, heavily damaging two building and forcing the on-going evacuation of nearby homes and businesses.
Ontario's solicitor general says the province has launched an investigation and that officials in the municipality of Chatham-Kent are working with the provincial investigation.
Chatham-Kent Fire Chief Chris Case says the province needs to send help from the Ministry of Natural Resources before the investigation can move forward.
"To be clear, I need someone to come and ascertain where the gas is coming from and how we're going to stop it before we can do any work," he says. "We literally have a rubble pile with a toxic, corrosive and explosive gas coming up through the floor."
Case says it's hard to determine how many people have been displaced by the incident.
"Because as you can imagine, some people self evacuated last night and went to stay with friends and relatives," he says. "There was a very small number last night the sought assistance, but we know from experience, that number will increase over the next couple of days as people can no longer stay with friends and relatives."
Evacuation efforts got underway immediately after a gas alarm went off around 4:30 p.m.
Mayor Darrin Canniff says there's no doubt that first responders saved lives Thursday night.
"If anybody has seen the pictures of the scene and the explosion, you know that if you were right in the heart of that, it wouldn't have been good," he added.