An ongoing Ontario Fire Marshal investigation into the fatal fire at 191 Grenfell St. has revealed the home had multiple smoke alarms, but only one of those had batteries in it at the time of the fire.

A fire erupted on the night of Saturday, Oct. 1, inside the rooming house where five people lived. Despite a quick emergency response and valiant neighbours on the scene to help, three people were killed.

As the OFM investigates, it has released a few findings. It says the fire started inside a back room of the home, and there is no evidence of anything suspicious regarding the cause.

On Friday, Rick Derstroff with the OFM told CBC News the investigation found multiple smoke alarms inside the home. He was unable to confirm how many, but said all but one of them were without batteries at the time of the fire.

"Our engineers were able to determine that [the unit with batteries] should have been operating," Derstroff said, but added that the unit was "not well placed," which may have added a delay before it was activated.

Derstroff pointed out how common it is for people to take the batteries out of their smoke detectors when they're being activated by people cooking or other normal activities. He said people should know that many modern smoke alarms have a "nuisance button," which works like the snooze button on an alarm clock. Pressing it will deactivate the alarm for just a few minutes before re-arming it automatically.

The OFM said it will probably not be able to release its findings about the cause of the fire for several weeks.