A 14-year-old boy, chilled from helping his father shovel out their car, died after climbing into the running vehicle to warm up, The Boston Globe reported.
Witnesses said the father collapsed on a snowbank after yelling, "He's not breathing, He's not breathing." He was hospitalized in serious but stable condition, the newspaper said.
Less than 2 miles away, a man in his 20s was found dead inside a car about 4:40 p.m. He apparently had been in the car for hours before being found.
In a third case in East Boston, a brother and sister, ages 4 and 7, were found unconscious shortly before 5 p.m. inside a car. They were taken to a hospital in time and were expected to survive, police said.
The incidents prompted police to issue warnings about the threat of carbon monoxide poisoning from vehicle exhausts being plugged with snow. They also warned about the need for proper ventilation for indoor fireplaces and noted barbecue grills should not be used indoors.