A memorial service for the 23rd anniversary of the Oklahoma City bombing paid special tribute to the late Rev. Billy Graham, who visited the city four days after the attack to hold a public prayer service.

Graham traveled to Oklahoma City the Sunday after the April 19, 1995, explosion at the Alfred P. Murrah federal building that killed 168 people and injured hundreds more.

Organizers of Thursday's service selected six audio clips from Graham's 1995 sermon on faith and resiliency and played them as a singer performed a gospel song to the crowd of about 1,000 at the Oklahoma City National Memorial and Museum.

Memorial director Kari Watkins says Graham acted as "pastor-in-chief" and helped the community begin to heal after the bombing.

Graham died Feb. 21 at age 99.