Oklahoma City Bombing: Survivors, Family Members Mark 15 Years Since Deadly Attack

OKLAHOMA CITY (CBS/AP) Oklahoma City bombing survivors and family members gathered to commemorate the 15th anniversary of the federal building's attack and remember those who died.

"We have chosen strength, we have chosen optimism, we have chosen freedom, we have chosen to move forward together with a level of unity that is unmatched in any American city," Oklahoma City Mayor Mick Cornett said at the ceremony, held on a cool, overcast morning.

Hundreds of people attended Monday's event at the Oklahoma City National Memorial to remember the 168 people killed in the April 19, 1995, explosion.

More than 600 others were injured in the attack at the Alfred P. Murrah Federal Building.

Attendees remembered the dead with 168 seconds of silence. Before the ceremony, some family members visited the site of the razed building, where there are chairs that honor the bombing victims.

Timothy McVeigh and his Army buddy Terry Nichols were both convicted for the bombing. McVeigh parked an explosive-filled truck in front of the building. He was executed in 2001. Nichols, who helped build the bomb, is serving multiple life sentences at a federal prison in Colorado.

The pair was motivated by a mistrust of the American government and anger over the federal siege of the Branch Davidians, a heavily-armed religious group in Waco, Texas, and the deaths of several members of one family in a confrontation with the Bureau of Alcohol, Tobacco, and Firearms at Ruby Ridge, Idaho.