Parts of US swelter under extreme heat as residents told to take precautions

A worker takes a drink from a water bottle as he unloads a trailer in sweltering Weldon Spring, Missouri (AP Photo/Jeff Roberson)

Extreme heat alerts continued for tens of millions of people in the United States on Tuesday as cities including Chicago broke records at the start of a week of sweltering weather.

States in the Midwest started to bake on Monday in what the National Weather Service called a dangerous and long duration heat wave that was expected to stretch from Iowa to Maine into at least Friday.