A 23 year-old mother from New Jersey and her 1 year-old son are dead after a freak set of circumstances following last weekend's winter storm. The family's 3 year-old daughter is in “very critical” condition at St. Joseph’s Regional Medical Center in Paterson.

So what caused this?

Northjersey.com reports that the women's husband was shoveling snow as the rest of the family sat in their car to stay warm. The snow had clogged the tailpipe of the car allowing deadly carbon monoxide to build up in the car.

Police Detective Andy White said that the husband had been shoveling for about twenty minutes. When the Passiac, NJ man went to check on his family couldn’t wake them up.

The identity of the father could not be learned immediately.

When police arrived at the scene they found that the mother and children had been pulled from the car, and neighbors were trying to revive them with CPR, according to Detective White.