US storms: Millions under flood warnings in north-east

Millions of people in the north-eastern US are under flood warnings, with intense thunderstorms expected to bring more dangerous conditions.

At least one person died in New York state as flood waters swept through streets and left drivers stranded.

The woman in her 30s drowned on Sunday after she was swept away while trying to evacuate her Hudson Valley home.

Governor Kathy Hochul said there were more missing people and declared a state of emergency for two counties.

"The amount of water is extraordinary," she said.

Thousands were also left without power. As of Sunday evening, some 12,000 homes were thought to be without electricity in New York state.

Videos of the conditions showed deep, brown flood water rolling through streets at a quick pace, flooding homes and in some instances moving cars.

Large areas are expected to see heavy and persistent rainfall as well as thunderstorms on Monday, the National Weather Service (NWS) said in an alert.

It said Vermont and north-eastern New York were the areas most at risk. People there have been urged to stay at home if possible and to check road conditions before driving.

The NWS added that several inches of rain were also expected to fall on Tuesday morning.

Meanwhile, more than 1,000 flights to New York airports have been cancelled as a result of the weather.

Many factors contribute to flooding, but a warming atmosphere caused by climate change makes extreme rainfall more likely.

Extreme heat is forecast for the south-western US this week, including Arizona, where the NWS said conditions were "rivalling some of the worst heat waves this area has ever seen".