Several NYC subway stations flooded on Monday night, causing severe delays and closures after rain drenched parts of NY, NJ and CT.

The heavy downpours wreaked havoc across the city with footage showing commuters overwhelmed by floodwaters in various subway stations.

In New York and New Jersey, flooding impacted some subway lines and other mass transit services, including the No. 1, 2 and 3 lines which was severely disrupted in Manhattan due to flooding. Service has since resumed in both directions with residual delays.

Two people in New Jersey were killed after their vehicle was swept up in flood waters during a storm that moved across the U.S. Northeast overnight, authorities said Tuesday.

Transit agencies in the New York City area were promising a fairly smooth commute with some lingering delays on Tuesday, the morning after heavy rain pummeled the region, flooding parts of the subway system, inundating major roads and causing long flight delays.

"Flooding can be deadly and often strikes with little or no warning. Streets, basements, and below-grade spaces can fill with water in minutes. If you live in a basement apartment or low-lying area, be ready to move to higher ground,