Millions of people in New York City and a large swath of the north-eastern US were stuck at home under road travel bans and blizzard warnings on Monday as heavy snow and strong winds intensified, creating whiteout conditions in the densely populated region.

Blizzard warnings stretched from Maryland to Maine. Cellphones across New York City received wailing push alerts on Sunday night announcing a ban on non-emergency travel on all streets through noon Monday because of “dangerous blizzard conditions”. Rhode Island and New Jersey implemented similar restrictions, the Guardian reported. 

More than 5,000 flights in and out of the United States were canceled for Monday, according to the flight tracking website FlightAware. Most were canceled in New York, New Jersey and Boston.

The storm caused power outages that left more than 300,000 customers in the dark along the east coast early on Monday.