The Nevada man behind a shooting spree in a Midtown Manhattan office building may have originally been targeting for the NFL headquarters, sources say.

A fifth shooting victim -- an NFL employee, according to Commissioner Roger Goodell -- was injured and taken to the hospital in critical condition, officials said. That victim was listed in stable condition on Tuesday morning, according to a source familiar with the individual's status.

The gunman suspected of targeting the National Football League headquarters in New York, killing four, was a former standout football player at two Southern California high schools.