Huge swathes of New York City have been warned to brace for flash floods as thunderstorms wreak havoc on the region.

The National Weather Service raised the alarm on Monday night as the deluge intensified across the Northeast.

‘At 5:42 p.m., local law enforcement reported thunderstorms producing heavy rain across the warned area,’ the NWS warned. 

Between 1 and 2 inches of rain have fallen, and additional rainfall amounts of 1 to 2 inches are possible in the warned area. Flash flooding is already happening.

‘Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas.’ 

Flash flood warnings are impacting Staten Island, the Bronx, Brooklyn, Manhattan, Queens and Westchester County.

These warnings will likely remain in place until at least 9.45pm.

Shocking footage of the deluge has started circulating on social media, showing gas stations overrun with water, and cars submerged in floodwaters. 

Cars stuck in heavy traffic as the rain battered down and flooded the roads in New York

Large areas of New York City have been advised to prepare for flash floods as thunderstorms cause disruptions in the region. Pictured: Photographer Dan Martland captures lightning striking NYC World Trade Center on Monday, July 14.

Stunning images taken by photographer Dan Martland show the moment lightning hit the World Trade Center. Meanwhile, commuters on the 1 train through Manhattan witnessed their carriage starting to fill with water.

The passengers squatted on the chairs of the train and held their belongings up off the ground as the train pulled into 23rd Street on Monday night submerged in rainwater. 

Across the border in Union County, New Jersey, the weather service has warned that ‘life-threatening flooding was possible.’

Throughout the Northeast, more than 50 million Americans are now under varying levels of flood warnings. 

Residents in the worst hit areas have been warned to ‘turn around, don’t drown when encountering flooded roads.’   

‘Most flood deaths occur in vehicles,’ the weather service warned. 

‘Excessive runoff from heavy rainfall will cause flooding of urban areas, highways, streets and underpasses as well as other drainage areas and low lying spots.’

Flash flood warnings urge residents in flood-prone to take action swiftly. This includes moving to higher ground to avoid rising waters.

‘A flash flood warning is issued when a flash flood is either imminent or already occurring,’ the weather service warned.

‘A flash flood is a sudden and violent inundation that can develop within minutes to hours, and it can even happen in areas not currently experiencing rainfall.’

Residents in the worst hit areas have been warned to ‘turn around, don’t drown when encountering flooded roads’

The National Weather Service raised the alarm on Monday night as the deluge intensified across the Northeast

People in a flood prone are or camping in a low lying spot are urged to seek higher ground as a first step, and to follow evacuation orders as they’re issued by local authorities.

‘Before leaving, secure your home by locking it. If time allows, disconnect your utilities and appliances. This reduces the risk of electrical hazards during flooding.’

Impacted residents are urged to avoid their basements or any submerged areas with electrical cords or outlets to avoid an electrical accident. 

‘If you notice sparks or hear buzzing, crackling, snapping, or popping noises, evacuate immediately. Avoid any water that may be charged with electricity.

‘Never attempt to walk through floodwaters. Even just 6 inches of swiftly moving water can forcefully knock you off your feet.’

The warning comes a week after at least 132 people tragically died during a flash flooding event in Texas. At least 101 people are still missing.