The city fire marshal is investigating an early morning house fire in Waterloo that left two children dead and a woman hospitalized on Thursday (March 15, 2018).

All three people were initially rescued from the burning home and taken to local hospitals, Waterloo Fire Chief Pat Treloar said. Two of those who were taken from the home later died.

"We've just recently confirmed that there's two fatalities resulting from this fire," Treloar stated. "We're confirming that the two fire fatalities were children."

The boy and girl were pronounced dead at a Waterloo hospital. The woman was transferred to University of Iowa Hospitals and Clinics in Iowa City, authorities said.

Firefighters were called to the one-and-a-half story home at 1815 Commercial Street shortly after 4AM. According to Treloar, a girl was able to escape the burning home through a window and flag down a passing motorist for help. Treloar said crews got to the scene and extinguished the fire fairly quickly, but encountered some tough conditions when they arrived.

"Crews faced zero visibility with heavy, heavy black smoke in the structure," Treloar explained. "They were able to locate three of the victims upstairs. They were able to bring one out the back door and then two of the fire victims were extricated through an upstairs window to firefighters waiting on a ladder."

The victims haven't yet been identified.

Treloar isn't sure if there were any working smoke detectors in the home.

"There may've been," the fire chief said. "We found an area on the wall where there appeared to be one, but our crews did not hear them going off when we arrived. There again, that is not to say that they were not functioning."

According to Treloar, investigators are still working on what caused the fire.

"We're confident that we know where the fire started -- we're still working through possibilities of why it started," Treloar said. "There were about a dozen dogs and cats in the basement of the home. Some of the pets also died in the fire.

Photo By: Elwin Huffman - Townsquare Media