The storm Ida is causing chaos in the multimillion-dollar city of New York, where more than 170 millimeters of rain fell in just over six hours.

This has led to extensive floods, including in the city's metro system.

Pictures on social media show water rushing over subway platforms and trains and all traffic in the subway system has been stopped.

"Stay away"

New York Mayor Bill de Blasio calls Ida a "historic weather event" and urges residents to stay home and not take to the streets.

"Stay away from the streets and let the rescue workers do their job," Bill de Blasio wrote in a Twitter post.

Nine people have died in New York City, many of them trapped in water-filled basements, police and de Blasio said.

Several states were affected

The governors of New Jersey and New York have declared a state of emergency in their states.

Philadelphia is also affected by heavy rainfall.

The storm Ida was initially classified as a hurricane but has later been downgraded.

Earlier this week, it hit the southeastern United States hard.

It caused extensive property damage, extensive power outages and claimed at least six lives in the states of Alabama and Louisiana.