NFL teams honor 15 year anniversary of 9/11

A view of the flag outside Lucas Oil Stadium prior to the game between the Indianapolis Colts and Detroit Lions.

Seattle Seahawks offensive tackle Bradley Sowell, quarterback Russell Wilson and tight end Luke Willson join arms during the national anthem.

A view of the cleats worn by Indianapolis Colts punter Pat McAfee.

Jacksonville Jaguars middle linebacker Paul Posluszny (51) carries an American flag during intros prior to a game against the Green Bay Packers.

Vice President Joe Biden (blue suit) and Philadelphia Eagles head coach Doug Pederson (left) help hold a large American flag with members of the military during the national anthem.

Former president George W. Bush and former first lady Laura Bush attend the Dallas Cowboys' game against the New York Giants.

View of shoes worn by New York Giants wide receiver Odell Beckham Jr.

New York Jets center Nick Mangold runs onto the field with the American flag before a game against the Cincinnati Bengals.

Fans listen to a message from President Barack Obama before a game between the New York Jets and the Cincinnati Bengals.

Jacksonville Jaguars defensive end Dante Fowler and center Brandon Linder hold the American flag during the national anthem.

Fans hold up a sign regarding 9/11 during the first half of the game against the San Diego Chargers.

View of cleats worn by Tennessee Titans linebacker Avery Williamson

A large American flag is displayed on the field during the national anthem before a game between the New Orleans Saints and the Oakland Raiders.

View of the 9/11 decal on the back of the Minnesota Vikings helmet.

Shoes worn by Houston Texans running back Lamar Miller.

Atlanta Falcons wide receiver Mohamed Sanu wears cleats in recognition of the 9/11 anniversary.

A United States flag flies outside EverBank Field prior to the game between the Jacksonville Jaguars and the Green Bay Packers.

First responders rehearse holding the flag before the game between the Kansas City Chiefs and San Diego Chargers.

Flags fly outside Lincoln Financial Field prior to action between the Philadelphia Eagles and the Cleveland Browns.

A close-up view of a 9/11 pin on the shirt of Tennessee Titans head coach Mike Mularkey.