An early morning fire on Tuesday ripped through a home in rural Indiana, killing six including four children, and authorities have reason to believe the fire was intentional, a report said.

WTHR reported that an unnamed source from Cass County, who was at the scene, raised the possibility. Indiana State Police Sgt. Tony Slocum told The Associated Press, "We're going to consider it a criminal investigation until we find out otherwise — it is all-encompassing."

Slocum told The Associated Press that crews assisted by cadaver dogs late Wednesday afternoon found two bodies in addition to those of an adult male, an adult female and two children recovered earlier. Slocum said he did not know the ages or the genders of the two latest bodies found.

The report said the dead included a 42-year-old man and his 10-year-old daughter. The body of a 25-year-old woman was also recovered at the scene, along with her 3-month-old boy, a 1-year-old girl and a 3-year-old girl.

Neighbors reported the fire about 2 a.m. Wednesday at the home north of Indianapolis. Two Cass County sheriff's deputies arrived within minutes later and attempted to enter the home but were turned away by flames and heat, Sheriff Randy Pryor said.

Two adults escaped the fire and were taken to a local hospital. Pryor said the two survivors have spoken to investigators.

The house was largely engulfed in flames when firefighters arrived, preventing any rescue attempts, New Waverly Fire Department Lt. Steve Crispen said.

The building's roof collapsed after fire gutted most of the interior of the two-story, wood-frame house, Crispen said.

Firefighting efforts were hindered by a lack of fire hydrants near the house. Fire crews ran out of water and had to wait for about five minutes for more tankers to arrive, Crispen said.

"It's pretty numbing when the initial dispatch is telling us people are entrapped in the structure and they're saying multiple people," Crispen said. "It's one of the toughest days I've probably had in my life."

Three state fire investigators were at the scene to determine the cause of the blaze, State Fire Marshal James Greeson said, adding that the task ahead would not be easy.

"We have an excavation unit in there that is going to systematically pull this apart, so we can get in and actually do our investigation," Greeson said.

The Associated Press contributed to this report