Investigators said Thursday that a cigarette is to blame for a fire at the Quaker Valley Mall in West Warwick.
Surveillance video shows what ignited Tuesday's fire, which was fed by natural gas spewing from the gas line at the back of Pinelli's. The restaurant had permanently closed the day before.
There was some concern that, the day after Pinelli's closed, a fire erupted.
"We want to make sure that the people in that neighborhood, we can allay their fears that this was not an arson fire. This fire was started with a carelessly discarded cigarette," state fire marshal John Chartier said "Unfortunately, where this fire starts is also where the gas main enters the building."
The security camera video -- shared only with NBC 10 -- shows a worker from the restaurant pitch a cigarette into a plastic bucket.
"You can see them discard that cigarette, and then go back in the building, and go about their work. And approximately 35, 37 minutes later, somewhere in that time frame, you can see the beginning of this fire start," Chartier said.
The smoldering fire grows to flames and begins to interact with the gas meter on the back of the building. The West Warwick Fire Department is called.
A representative of National Grid said there was no leak at the gas meter. The flames reached the plastic riser to the meter that melted, leading to the gas to catch fire.
"The gas meter is destroyed by the heat of the fire. As soon as you've got that, then you've got a gas-fed fire," Chartier said.
Protocol is to let the fire burn until the natural gas can be shut off by National Grid. That happened a half hour later.
"Had this been in a building that was wooden construction, or had this building been in a configuration where it was in an alley, you would have had a major fire as a result of this, all from a carelessly discarded cigarette," Chartier said.
The state fire marshal said it was a unique set of circumstances and the fact that it was caught on camera is going to make for a great training and prevention video.