A National Football League employee was seriously injured in a shooting Monday at a midtown Manhattan building that houses the NFL's offices and some of the country's top financial firms, commissioner Roger Goodell said in a memo to employees.

NFL Commissioner Roger Goodell revealed one employee was hospitalized after a shooting at the league's headquarters in Manhattan left five dead before the gunman took his own life.

NFL employees were told to shelter in place Monday evening as a gunman opened fire inside the New York City building that houses the league's headquarters, killing four and leaving another in critical condition.