@ashleymarand via nbcnewyork.com

Crowds at Penn Station after the Long Island Rail Road suspended service because of an electrical problem.

Updated at 11 p.m. ET: Service out of New York's Penn Station is returning back to normal after a commercial power outage resulted in suspension of all train service in and out of the station on Wednesday night, the busiest travel night of the year.

At issue was a power outage caused by Con Ed work, the New York Post reported. The outage turned off the switches around 5:30 p.m., during the crush of rush hour. All service was suspended temporarily -- resulting packed crowds at Penn Station on the busiest travel night of the year. 

For a while, passengers were not allowed into the station, due to overcrowding, but the crowds had mellowed by 9 p.m. ET and the station reopened.

The Long Island Rail Road resumed its service close to its modified service, the MTA said on its website, although delays and cancellations were expected.

The initial fury and frustration was felt immediately on social media.

"Oh my!!! #lirr NJT and Penn station SHUT DOWN on the busiest travel night of the year. Enough is enough for us!," said Leslie on Twitter.

Mother Nature (mostly) cooperates during travel rush

"I've tried to be understanding because of Sandy, but "Switching problems" at Penn Station the night before Thanksgiving?!?! #njt #lirr," tweeted Rob Celletti.

There was also some humor.

"Good thing New Yorkers and New Jerseyans are a famously calm people who always handle unexpected delays with tact. #njt #lirr," wrote Chris Heller on Twitter.

More on Twitter from NBCNewYork.com