Tens of millions in the US are under dangerous heat warnings

Extreme heat alerts have continued for millions of people in the United States, with cities like Chicago breaking records at the start of a week of sweltering weather. The Midwest and Northeast were under heat warnings or watches, with officials announcing the opening of cooling centers and urging people to limit outdoor activities when possible. Phoenix has experienced the most heat waves since 1936, with temperatures reaching 112 F (44.4 C) on Saturday.