murrah building in downtown oklahoma city. >> get back. everybody, get back. >> get back. >> they have found a bomb in the building. >> 90 minutes after the blast, a new panic radiates through the streets when first responders come across what appears to be a second bomb. the rescue operation is suspended and a four-block area is quickly evacuated. it is, thankfully, a false alarm, but precious moments have been lost. by the time the rescue resumes, investigators have swarmed the area. >> first question has been answered, was this just a freak accidental explosion of some kind or was it intentional? we know now. >> it is quickly determined that the explosion at the federal building was caused by a truck bomb. >> there are certain things you