Two children apparently froze to death while sleeping inside a van parked in a garage for a casino in Detroit, police said. The children, a 2-year-old girl and a 9-year-old boy, were among five others sleeping along with their mother inside the vehicle on Monday.

The deaths remain under investigation, though authorities believe the 2-year-old and 9-year-old froze to death early Monday.

Investigators are shaken by the unimaginable tragedy that one phone call could have prevented. Two children were frozen to death inside a van parked at Hollywood Casino at Greektown.