Oklahomans paused Saturday morning at the Oklahoma City National Memorial to remember the 168 people who died 13 years ago in the bombing of the Alfred P. Murrah Federal Building.

The attack on April 19, 1995, remains the deadliest act of domestic terrorism in U.S. history.

As has become custom, the anniversary service held at the memorial — part of which sits on the site of the former federal building — was both simple and poignant.

"We are here today to remember those who were killed, those who survived and those changed forever," said Oklahoma City Police chaplain Jack Poe. "May this memorial offer comfort, strength, peace, hope and serenity."

At 9:02 a.m., the exact moment of the bombing, those attending the service observed 168 seconds of silence for each of the bombing's victims. The names of each of those killed in the bombing were also read aloud.

Before the ceremony, family members of the victims placed wreaths and mementos on the permanent chairs, each one representing a victim of the bombing.

"The evil act perpetrated here illustrated the depths of human depravity," Gov. Brad Henry said. "But Oklahomans met tragedy with triumph. From such a horrible crime came tales of astounding goodness.

He added, "That aftermath came to show the innate goodness of humanity."

Rudy Guzman of Castro Valley, Calif., is the brother of Marine Capt. Randolph A. Guzman, who died on the sixth floor of the building in the U.S. Marine Corps recruiting office.

"It felt good being up there saying my brother's name," Rudy Guzman said. "It was a great way to honor him."

As Guzman stood by a chair bearing his brother's name, he said he has had to learn how to deal with the tragedy. "Day by day you think of the good things," he said.

Guzman said family members and survivors have developed a sense of family over the years. He said, "It's a family brought together in tragedy, but we're here to help each other out."

Deb Hodges, the wife of bombing victim Gene Hodges Jr., killed on the seventh floor of the building, said, "It doesn't get better. It gets different. You adjust but you never forget."

Later Saturday, a national media symposium featuring ABC anchorman Bob Woodruff and his wife, Lee, was scheduled to be held at the National Memorial.

He was critically injured while reporting on the Iraq war in January 2006 when his vehicle struck a roadside bomb.

The nine-story federal building was destroyed when a cargo truck packed with 4,800 pounds of ammonium nitrate and fuel oil was detonated near its entrance. Besides the 168 who died — including 19 children — more than 800 others were injured.

An Oklahoma Highway Patrol trooper caught Timothy McVeigh less than two hours after the bombing. McVeigh was convicted of federal murder charges before being executed on June 11, 2001 at an Indiana prison.

Terry Nichols, who met McVeigh in the Army, was convicted on federal and state charges connected with the bombing and is serving multiple life sentences in a Colorado prison.

During the trials of McVeigh and Nichols, prosecutors called the bombing a twisted attempt to avenge the deaths of about 80 people in the government siege at the Branch Davidian compound in Waco, Texas, exactly two years earlier.