CNN  — 

At least four people are dead after a powerful storm brought dangerous flooding and travel disruptions across the East Coast and knocked out power to more than 620,000 homes and businesses in the Northeast, which faces cold temperatures and concentrated snowfall on Tuesday.

The storm system carved a chaotic path up the East Coast, leaving a man in Pennsylvania and a woman in South Carolina – both in their 70s – dead after their vehicles were submerged in high water, local officials reported. Two other deaths were reported in Maine and Massachusetts.

As the storm walloped the Northeast Monday, it unleashed 2-4 inches of rainfall across the region within a 24-hour period. The heavy rainfall triggered flooding that engulfed cars, trapped drivers on inundated roadways in New Jersey and Connecticut, and prompted water rescues in New Hampshire and Maine.

Though the storm moved into Canada late Monday and rainfall has largely subsided in the Northeast, impacts will linger over New England on Tuesday. The threat of flooding remains for multiple communities where river levels are still peaking.

Parts of western New York and Pennsylvania may also see snowfall, along with parts of the Great Lakes and Appalachians on Tuesday.

Temperatures are set to plummet to the 30s and 40s across much of the Northeast, as more than 620,000 homes and businesses in the region remained without power early Tuesday, according to poweroutage.us. The vast majority of outages are in Maine, where 432,000 are in the dark.

Fully restoring power to some Maine residents may take several days, warned Central Maine Power, a utility that serves more than 600,000 customers.

The conditions have prompted school closures or delays in several districts in Maine and New Hampshire.

Schools in Paterson, New Jersey, were also closed until further notice after the mayor declared an emergency Monday afternoon in anticipation of flooding from the rising Passaic River, saying he “expects the worst” of flooding to happen in the next 24 hours.

In nearby Little Falls, the mayor urged residents to evacuate before midnight Monday due to flooding of the river, which authorities previously warned could be “catastrophic.”

“Residents remain in their homes at their own peril,” Mayor James Belford Damiano said. “Flooding may cause dangers that may prohibit rescues as early as the overnight hours.”

Flood risk may be exacerbated in some New England states as heavy rain falls on top of an established snowpack. This may lead to rapid snowmelt and a sharp increase in flood threat.

The storm has been advancing up the East Coast and into the Northeast since the weekend, leaving at least four people dead from South Carolina to Maine.

In Mount Pleasant, South Carolina, a 72-year-old woman was found dead on Sunday after becoming trapped as her car was fully submerged in water, according to the Charleston’s Post and Courier newspaper. The area received more than 6 inches of rain that day.

Another person, a 73-year-old man, also died after his car became immersed in high water caused by heavy rainfall in Pennsylvania on Monday, according to coroner’s office in Lancaster County.

A 40-year-old man was killed in Windham, Maine, on Monday after a tree piece fell on him while he was on his roof trying to clear another part of the tree off his home, authorities said.

Also on Monday, strong winds and rain in Massachusetts caused a tree to collapse on a small travel trailer in Plymouth County, inflicting severe head trauma on the 89-year-old man inside, the local district attorney said. The man was rescued from the trailer but later died from his injuries.

Snow arrives in Great Lakes and Appalachians

Cold air trailing behind the storm has ushered in winter weather alerts across 10 states in the Great Lakes, Appalachians and interior Northeast.

Up to a foot of snowfall could be seen in parts of northwestern New York and Ohio as well as central Pennsylvania and West Virginia, where winter storm warnings are in effect Tuesday morning. Wind gusts up to 50 mph are forecast in the impacted area.

Surrounding areas could get between 1 to 6 inches of snow while impacted areas around the Great Lakes are forecast to receive up to 7 inches, according to the weather service.

CNN Meteorologist Taylor Ward and CNN’s Michelle Watson, Danny Freeman, Jamiel Lynch, Caroll Alvarado and Celina Tebor contributed to this report.