When the lights went out, the air-conditioning stopped and communication lines went dead most Manhattan workers must have shared the same thought.
Thousands unable to get home had to bed down outside
Only after they had filed out of the skyscrapers to find the city had suffered a massive power cut did the fears of another terrorist attack begin to ease.
It must have come as a relief to New Yorkers, who spoke of chaos but little panic as the worst power outage in history brought cities across America and Canada to a standstill.
People were stranded on underground trains, airports closed and roads became gridlocked as millions of commuters attempted to get home.
Those who decided to walk included Manhattan worker Lucy, who left her office at 1630 (1200 GMT) arriving at her New Jersey home at midnight.
"I tried to get a ferry from NYC, but they soon stopped from the pier I walked to as they all ran out of fuel," she said.
"The queues were terrible - people fainting everywhere from the heat."
In the Canadian city of Toronto, every available technician was called in after lifts in many buildings suddenly stopped, trapping people inside.
Tens of thousands of people in Manhattan who could not get home found themselves without shelter and were forced to spend the night in the open.
There was a party atmosphere in many parts of the city until the early hours when the need for sleep overtook them.
Public benches were snapped up and covered doorways were turned into mini-shelters.
Forced to sleep on an awning-covered terrace outside an office block, Dai and Keiko Oyama used their outer garments as bedding for their three-year-old daughter.
"What else can we do," Keiko Oyama told French news agency AFP. "We live upstate in Westchester. We're just hoping the power will come back and then we'll try the train station."
While some hotels were criticised for not opening their doors to the stranded and there were tales of looting in Ottawa, many people appeared to rise to the occasion.
Red Cross volunteers supplied drinking water outside New York's Grand Central Station to stop people suffering from dehydration.
RECENT US BLACKOUTS
1996: 4m people hit by electricity outage across nine states
1977: lightning strike leaves New York without power for 25 hours
1965: power loss in north-east US and southern Canada hits 30m people
Candle-lit bars and pubs in many cities stayed open to offer relief to some thirsty people.
Carl in Mississauga, just outside Toronto, told BBC News Online: "Many people helped direct traffic until the police arrived. Fuel prices at some gas stations actually went down, although there were very long line-ups."
An actor - who plays an FBI agent in the US television show The Sopranos - turned real-life cop to help those directing traffic at a gridlocked intersection in the evening rush hour in Manhattan.
"This is why [New York] is the greatest city in the world," he said. "Because people will stop and do this."
For many though, the incident brought back memories of 11 September.
Jessica Nottes was on top of the Empire State building when the power went out.
"We had to walk down 86 flights of stairs," she said. "I kept thinking about the Twin Towers and how I would get down. But everybody was calm."
The question on many New Yorkers' lips though was why, after the events of 11 September, should a major emergency still throw the city into such chaos?
"It shows just how unprepared New York is for a crisis such as this," said Lucy. "You would have thought after 11 September they would have had some better contingency plans."