LANSDALE, Pa. -- Officials said Friday morning they won't know the exact cause of a 4-year-old quadruplet's death at a squalid home until toxicology tests come back in several weeks.

An autopsy found that malnutrition was a factor in the death, Montgomery County First Assistant District Attorney Risa Vetri Ferman said Friday. She did not yet know if any state or local agencies had been working with the family.

Towamencin Township police received a call at around 7 a.m. Thursday that a child was unresponsive at the home at the Morgandale Condominium. They arrived to find the boy's father performing CPR on the child outside the two-story townhouse complex.

Police then took over CPR efforts, but the child was pronounced dead at the hospital, said Joseph Kirschner, police chief in Towamencin Township, about 30 miles northwest of Philadelphia.

Montgomery County District Attorney Bruce Castor said that the boy's parents, Jim and Tammy Seymour, called 911 after they found he wasn't breathing at 6:30 a.m. Thursday.

Castor told WCAU-TV in Philadelphia that the house has been deemed uninhabitable because of the filth inside. Kirschner described the scene as they entered the home.

"It was very tight. A lot of dirty clothes, animal feces, animal waste, just deplorable living conditions, quite frankly," Kirschner said.

Neighbors said that they never saw the windows of the apartment open and the shades were always down. Neighbors also said they never saw the children or the family's dogs outside.

The boy is one of a set of quadruplets. The three other quadruplets, along with an older girl, have been placed in foster care pending an investigation. Police said the three 4-year-old children were very weak and could not sit up straight on their own. They each weighed from 20 to 25 pounds and had to be carried out of the home, according to police.

Police said the boy's parents were questioned and released Thursday night.