PLEASE NOTE: *Do not* tweet emergency calls. Please call 911. If it is not an emergency, please call 311. #NYC #Sandy -- FDNY (@FDNY) October 30, 2012

With New York City inundated by Hurricane Sandy-driven storm surge, heavy winds, and emergencies throughout town, the FDNY is pleading with people not to use Twitter to call for help.

"PLEASE NOTE: *Do not* tweet emergency calls. Please call 911. If it is not an emergency, please call 311," the FDNY tweeted at 9:32 p.m. ET as the massive storm roared through the city.

It's not that the fire department categorically won't respond to calls for assistance on Twitter, however. It just doesn't want New Yorkers thinking they can depend on the microblogging service for help from the FDNY. "Was helping when needed via Twitter," the FDNY tweeted to CNET this evening. "Just didn't want it to be seen as an alternative to 911/311, which is always best."

But that the department felt the need to make a public declaration at or near the peak of the crisis not to tweet for help is testament to how important many people now consider Twitter during natural disasters and a wide range of other local, national, or global events. From presidential debates to political uprisings to the Olympic Games, Twitter has become indispensable as a tool for global discussion, coordination, message dissemination, and more. As Twitter user Richard Chen put it, "In times like this, it's the TV that's the 'Second Screen.'"

Throughout the day today, Twitter served many public roles related to Sandy. It was an information depot. It was a place to spread hoax photos. It was a broadcast medium for public officials like New York Mayor Michael Bloomberg, who used it to provide updates ("Storm surge peaked at 13.88 ft at the Battery. Now 9.81 ft & going down. Power outages and other serious issues remain") and encouragement ("I know things have gotten tough for NYC tonight. We are going to get through this together, as New Yorkers always do.") And Twitter has also been a place for people from all walks of life to work through their stress with comedy and jokes.

Clearly, the FDNY worried that because of demand on 911 services, people in trouble might assume they could get help by tweeting the details of their emergency. And that says a lot. Twitter is really not just for telling the world what you had for breakfast anymore.

For those in New York, Twitter has put together a list of emergency and non-emergency resources.