The National Weather Service urged people to avoid travel if a flash flood warning was in place for their area.

In Plainfield, New Jersey, two people were killed when their car was swept into Cedar Brook, city officials said. This comes days after two others were killed in severe storms in Plainfield on July 3.

A flash flood warning was in effect in New York City until 9:45 p.m., and New Jersey Gov. Phil Murphy declared a state of emergency. Middlesex, Morris and Somerset counties remained under a flood warning until 7:15 a.m. Tuesday.

New York and New Jersey hit by torrential rain and flash floods, forcing highway closures, suspending subway lines and flight delays.

Heavy rains during the evening brought flooding, road closures and power outages throughout New Jersey, which is under a state of emergency.

New Jersey is under a state of emergency after a flash flood caused at least two deaths in Plainfield and damage across Union County.

Officials in one county told residents to only dial 911 for life-threatening emergencies Monday night, according to a social media post from officials.

Camp Mystic's executive director began evacuating campers approximately 45 minutes after the National Weather Service issued a "life-threatening flash flooding" alert.

New York is cleaning up and trying to dry out after Monday night's torrential rains caused flash flooding and damage.

On Tuesday at 7:55 p.m. the NWS Raleigh NC released a flash flood warning in effect until 11 p.m. for Forsyth County.