Updated

A fire swept through a small home in Indianapolis on Saturday morning, killing a couple and two of their children and leaving two surviving siblings in "very critical" condition, a fire official said.

The home is adjacent to a busy Interstate 70 overpass, and a motorist on that highway reported the fire about 9:10 a.m., Capt. Rita Reith said. Subsequent 911 calls led crews to the home's exact location in an east side neighborhood.

Firefighters found the parents and their four children -- ages 14, 11, 8 and 6 -- unconscious inside the small bungalow-style home and brought them outside, starting efforts to resuscitate them on the lawn, Reith said.

"They knew they had victims inside the house, but they were not expecting six," she said.

Authorities said Lionel "Leo" Guerra, 47, and his 33-year-old wife, Brandy Mae Guerra, were pronounced dead shortly after arriving at Eskenazi Hospital.

The couple's 11-year-old son, Esteban Guerra, and 8-year-old daughter, Blanquita Guerra, were pronounced dead at Riley Hospital for Children, where their two siblings -- a 14-year-old girl and a 6-year-old boy -- remained in critical condition late Saturday afternoon.

"We have two children who are very, very critical condition," Reith said. "It's been a horrific morning for us."

Investigators do not suspect any foul play was involved in the fire, but Reith said its cause remains under investigation and there's no sign the home had working smoke detectors.

Reith said firefighters extinguished the fire in about 10 minutes.

One of the 911 callers reported that they had heard people yelling inside the home, which Reith described as about the size of a two-car garage, but investigators aren't sure what unfolded inside.

"They were awake if that's the case, but they still couldn't get out. Was the fire location and where they were located in the house not allowing them to get out? We don't know," she said.

The home sits in a lower-income neighborhood with a mix of small homes built next to an industrial corridor and a major interstate.

Hours after the fire, the tan single-story home's exterior showed few signs of fire damage, aside from soot blackening some windows. Reith said the interior suffered heavy fire damage.

The couple was married and the family had lived there for several years, she said.

Indianapolis has had eight fire deaths in 2014, including those killed in Saturday's fire, she said.