Safety experts say there are steps you can take to protect you and your family in a crowd.
First is to be prepared before a large scale event. Coordinate with family and friends where you will meet if separated.
Follow directions, don't ignore signs or barricades.
Stay aware and make it a habit of scanning a room or concert hall for the nearest emergency exit.
Lastly, in case of disaster, leave the area immediately.
"Also have to rely on the public to be more aware and to call 911 if you suspect anything, if you see something, say something," said Emergency Services spokesperson Shayne Enright.
Thousands gathered at the memorial to pay tribute to those who paid the ultimate sacrifice and to those who survived.
You may remember the story we did earlier this week about the Pearl Harbor survivor who was headed here from the mainland for the ceremony, he was bumped from the flight and didn't know if he would get here in time.
It may take drivers a little longer to get around this weekend. On Sunday, there will be lane and road closures for the Honolulu Marathon.