A 12-year-old girl in Illinois is dead and a 9-year-old girl is recovering from hypothermia after the snow fort they built collapsed on them, police said.

The girls were at a church in Arlington Heights, a suburb of Chicago, attending services with their families on Sunday when they decided to play outside, the Arlington Heights Police Department told Fox News.

After an hour had passed and the children still had not gone inside the church, their family members began to search for them and "found them underneath the snow."

CLICK HERE TO GET THE FOX NEWS APP

The girls were transported to a hospital, where the 12-year-old was pronounced dead. The 9-year-old was found to be suffering from hypothermia and was being treated, investigators said.

Foul play is not suspected in the incident, as police said it "appears to be a tragic accident."