US President Barack Obama urged Americans to honor first responders and men and women in uniform who keep the country safe as he marked the eleventh anniversary of the September 11, 2001 attacks.

“It’s a chance to honor the courage of the first responders who risked their lives – on that day, and every day since,” Obama said in his weekly radio and Internet address.

“And it’s an opportunity to give thanks for our men and women in uniform who have served and sacrificed, sometimes far from home, to keep our country safe,” he added.

Memories remain raw of the day when Al-Qaeda hijackers slammed two passenger planes into the World Trade Center in New York, destroying its iconic Twin Towers, and a third into the Pentagon building, in the nation’s capital.

A fourth plane crashed in a Pennsylvania field when the passengers valiantly overpowered the hijackers.

Almost 3,000 people were killed that day in the worst attacks on American soil.