Temperatures stayed below freezing as hundreds of thousands waited for their electricity to be restored after a devastating winter storm that has been blamed for at least 19 deaths across the US. In the latest incidents, icy weather contributed to the deaths of four St. Louis residents, city officials said Sunday. Two men died of suspected carbon monoxide poisoning after they tried to keep warm by burning coal on their stove. One man was found dead in his yard from possible hypothermia and an elderly man was found dead at the bottom of his home's stairs. "This is not over. As long as the power is still out, there are still people at risk," said St. Louis Mayor Francis Slay. Temperatures barely rose into the 20s Fahrenheit (around minus-6 Celsius) Sunday. City officials encouraged people to stay at temporary shelters, rather than try to tough it out in residences without power. The storm was blamed for at least 15 other deaths as it spread ice and deep snow from Texas to Michigan and then blew through the Northeast late Friday and early Saturday. Thousands of travelers were stranded by canceled flights, highways clogged by abandoned vehicles and stalled trains. By Sunday afternoon, about 350,000 customers of St. Louis-based Ameren Corp. had no electricity in a roughly 300-mile (485-kilometer) swath from Jackson, Missouri, northeast to Pontiac, Illinois, said spokeswoman Susan Gallagher. The utility would not estimate when power would be restored. At the peak of the outages on Friday, 510,000 customers were without power, Gallagher said. Hundreds of thousands also lost power in the other states hit by the storm.