9/11 and Unemployment?

As devastating as the human tragedy of 9/11 was, it is fortunate that the vast majority of people who worked in the WTC survived, either those on lower floors who were able to evacuate prior to the buildings’ collapse, or those who happened not to be in the complex that morning.

Likewise, some of the companies housed in the WTC survived, and some did not. Companies with data and infrastructure backup probably stayed in business while others operating at the margins did not.

I’m curious as to how many people employed in the WTC at the time of the attacks lost their jobs as a result, and what effect this had on the overall unemployment rate in NYC. If anyone is aware of any studies or srticles on this subject, I’d appreciate a link. Thanks.