(CNN) -- A freak fall snow storm slammed the Mid-Atlantic and Northeast on Saturday, leaving three people dead, more than 2 million households without power and thousands of air travelers stranded.
An 84-year-old man was napping in a recliner at his home in Temple, Pennsylvania, on Saturday afternoon when part of a large, snow-filled tree fell into his house and killed him "instantly," according to a state police report. With numerous downed trees in the area, rescue crews took two hours to "safely remove the victim."
Another person died while driving in Hebron, Connecticut, state emergency spokesman Scott Devico said.
A third person was killed in Springfield, Massachusetts, when a man in his 20s ignored police barricades surrounding downed power lines and touched a metal guard rail, which was charged, said city fire department spokesman Dennis Legere.
Predicting the system could dump as much as 18 inches of snow in some spots, Connecticut Gov. Dannel Malloy joined New York Gov. Andrew Cuomo, New Jersey Gov. Chris Christie and Massachusetts Gov. Deval Patrick in issuing emergency declarations for their respective states.
"It's like a blizzard, you can't see far at all," CNN iReporter Alban Ajro, 32, said Saturday night from Watertown, Connecticut. "This is the first time that I can ever recall this kind of storm happening before Halloween."
All domestic flights out of New Jersey's Newark International Airport were canceled around 4 p.m. Saturday, according to an announcement made at the airport. Frustrated passengers filled an array of long lines, trying to change their tickets in light of the storm.
Another airport in the Garden State, Teterboro, closed just after 2 p.m. before reopening hours later, the Federal Aviation Administration reported on its website. The FAA also reported major delays of, at times, over 5 hours at New York's two airports, John F. Kennedy and LaGuardia.
Richard Roth, a CNN correspondent, was among those affected when his Syracuse-to-Kennedy flight was diverted to Hartford because of the storm. He sat with his fellow passengers on the runway at Bradley International Airport for about four and a half hours, and -- roughly eight hours after arriving -- he was still stuck in the terminal.
"We're here in the dark now," Roth said Saturday evening. "There's no hope, at the moment, in sight."
The Connecticut governor acknowledged that conditions "are not very pleasant" at Bradley, where 23 flights have been diverted. He added, "They're trying to get people off their planes as rapidly as they can."
The early season snowstorm was the result of unseasonably cold air mixing with a storm system on the East Coast.
As of 8 p.m., the storm had already dumped 10 inches of snow in places as far afield as Ridgefield, Connecticut; Ogletown, Pennsylvania; and Terra Alta, West Virginia, according to the National Weather Service. Parts of New York and New Jersey especially got buried, including 15.5 inches in West Milford, New Jersey, and 12 inches in Harriman, New York.
Lesser, albeit still significant amounts were measured in other locales around the northeast, including 1.3 inches of snow in New York's Central Park as of 8 p.m. -- the most ever for this date since record-keeping began in 1869. Snow continued to fall Saturday night as the system moved over New England.
The storm's timing made it unique and caught some off-guard.
"We're used to a lot of snow here, but not this early," CNN iReporter Michael Majosky, 34, said from Windber, Pennsylvania. "We don't mind the snow -- it's pretty neat having it around Halloween."
Winter storm warnings were in effect Saturday evening for a swath of states, from Pennsylvania to eastern Maine. Along with heavy snow, high winds gusting up to 50 mph were possible.
Forecasters' predictions of power outages and downed trees in some areas bore fruit, as hundreds of thousands were without electricity as of Saturday afternoon. The reason is that the moisture content -- thus density -- of the falling snow was particularly high given temperatures hovering around the freezing point.
Malloy, the Connecticut governor, said early Saturday night that 50,000 to 70,000 customers were losing power every hour, with the leading utility Connecticut Light and Power reporting on its website about 550,000 without service at 9 p.m. Saturday. The governor cautioned that power crews are not out on the roads, and won't return until road conditions improve markedly.
"If you are without power, you should expect to be without power for a prolonged period of time," Malloy said.
About 715,000 customers were without power late Saturday in New Jersey, in addition to 333,000 in neighboring New York, according to figures reported Saturday evening by power companies in those states. Another 360,000 didn't have electricity in Pennsylvania due to the storm.
Other states were affected as well, including at least 7,000 households in Maryland, 6,300 in Virginia who get service from Dominion, and 1,400 Allegheny Power customers in West Virginia.
The storm had wreaked havoc on the roads, with Malloy noting "a large number of spin-outs and vehicles going off the road" in his state. He noted that -- in addition to the fatality -- a state trooper was injured in a crash.
And in Pennsylvania and elsewhere, CNN meteorologist Chad Myers warned that the wet snow would turn to ice in many spots overnight due to freezing temperatures, making road conditions even more perilous.
One positive is that the wintry weather shouldn't last too much longer.
By Sunday afternoon, the storm is expected to have passed the United States. Temperatures should warm by then -- including a high of 49 forecast for Sunday in New York, warming into the high-50s over the course of the week.
CNN's Greg Botelho, Greg Morrison, Sara Weisfeldt, Elizabeth Cherneff and Sean Morris contributed to this report.