Heavy rain and flash floods batter US east coast with emergency declared in NYC

Heavy rain and floods are hitting parts of the US east coast, causing flight cancellations and leaving drivers stranded in cities including New York.

A total of almost 50 million people in the US are under flood watches, and states of emergency have been declared in New Jersey and New York City, with state workers being sent home early. Airports in NYC, New Jersey and Philadelphia all reported significant flight delays and cancellations as the severe weather arrived on Thursday.

Flights leaving all three of New York's largest airports are delayed, and all inbound flights are being held until conditions improve, Sky's US partner NBC News reports. Planes have also been grounded at airports in Washington DC and Baltimore, Maryland.

A major highway in the New York borough of Queens was closed in both directions, with traffic cameras and social media posts showing vehicles stranded in deep water. Officials in New York have warned that heavy rain could also flood parts of the subway and basements.

People living in basements have been urged to move to higher floors and New Yorkers are being asked to avoid travel until Friday afternoon. The commuter rail system into suburban Long Island suspended trains on one of its busiest lines as officials pleaded with people to stay at home.

"Stay home this evening unless it's absolutely necessary for you to go out," Nassau County executive Bruce Blakeman told Long Island residents. Read more:World's oldest baby born in USGazan boy arrives in UK for urgent treatment Tornado warnings were also in place in New Jersey, and while no twisters were reported, more than 6,000 electricity customers have been left without power.

In some parts of Pennsylvania, National Weather Service warnings said there could be up to three inches of rain in just one hour, and a downpour flooded the streets of Reading. Up to four inches of rain have fallen in parts of Maryland and Washington DC, and the heavy rain is continuing, NBC reports.

Flood and severe thunderstorm watches are in effect for parts of Pennsylvania until Friday, with four to six inches of rain possible in some areas..