Mourners gather each April 19 at the former site of the Alfred P. Murrah Federal Building to observe the anniversary of the bombing, which injured hundreds.

Participants will observe 168 seconds of silence, followed by family members reading the names of their lost loved ones.

Organizers said attention also will focus on the killings of 32 people at Virginia Tech by a student who then killed himself.

"Violence obviously is happening," said Nancy Coggins, spokeswoman for the Oklahoma City National Memorial & Museum. "We hope there are ways we can reach out to them and offer support. They will be in our minds and in our hearts."

Coggins said the "fairly low-key" anniversary observance will be "a little more prominent" this year because former New York City Mayor Rudy Giuliani, who was mayor during the Sept. 11, 2001, terrorist attacks, will address the crowd.

After the ceremony, Ron Norick, who was the mayor of Oklahoma City in 1995, and Giuliani, a Republican presidential candidate, will discuss how they led their cities through acts of terrorism during a symposium at the museum.

In the federal building attack, a cargo truck packed with two tons of ammonium nitrate and fuel oil was detonated in front of the nine-story federal building on April 19, 1995.

Timothy McVeigh was apprehended less than two hours later. He was convicted of federal murder charges and was executed June 11, 2001. Terry Nichols, who met McVeigh in the Army, was convicted of federal and state bombing charges and is serving life prison sentences.

Another Army buddy, Michael Fortier, pleaded guilty to not telling authorities in advance about the bomb plot and agreed to testify against McVeigh and Nichols. Fortier was released from a federal prison in January 2006 after serving most of a 12-year sentence.