Investigators have released information involving a deadly house fire that killed two people in Waterloo last month.

According to Waterloo Fire Rescue officials, an accelerant was used in the deadly blaze at 536 Dawson St. on April 22, 2018.

Ashley Smith, 32, and her 9-year-old son, Jaykwon Sallis, both died from injuries suffered in the fire. They were among five people inside the two-story home when the blaze broke out. The other occupants -- a man, woman and girl -- all escaped the burning house through an upstairs back window. The two females suffered minor injuries and were treated a local hospital.

Firefighters found the front of the house fully engulfed when they arrived at the scene around 6:30 AM. They spent several hours at the location, extinguishing the fire and investigating the cause.

In a press release on Monday, officials revealed that a Waterloo Fire Rescue canine was alerted to the presence of an accelerant during the investigation. The city's fire marshal submitted that evidence to the Iowa State Crime Lab, which determined that a flammable substance was involved in the blaze.

No charges have been filed in the case, which remains under investigation.