SPRINGFIELD, TN (WKRN) – Four children were killed and two other people were injured in a Springfield house fire early Monday morning.

It happened on Poplar Avenue, between Perry Drive and Smith Street, around 3:30 a.m.

Upon their arrival, a woman alerted crews that there were people still inside the burning home.

Crews immediately began searching for the victims and working to knock down the fire.

Springfield Fire Chief Jimmy Hamill told News 2 four children, including a set of 2-year-old twin boys, a 4-year-old and a 7-year-old were killed.

The father and an 8-year-old girl were also taken to Vanderbilt University Medical Center. The man was last listed in very critical condition. The girl remains in stable condition.

“It’s devastating,” Hamill said. “This is the worst one I have ever been on with this many fatalities. It’s just terrible.”

A woman and two other children escaped.

The fire is thought to have started in the living room, though a cause has not yet been determined.

“It is not arson – [it was] not intentionally set,” Hamill said. “As far as the cause of the fire, we’re deeming it undetermined.”

The fire marshal and the Tennessee Bureau of Investigation are assisting in the investigation.