We report the experimental observation of a three- dimensional abruptly autofocusing effect by synthesiz- ing a radially distributed Airy beam with two counter- propagating Airy pulses in time. As the wave packet propagates in a dispersive medium, the radially dis- tributed Airy beam converges inward to the center point. Two Airy pulses counter-propagate toward each other to merge to form a high peak power pulse. As the result, the high intensity emerges abruptly as the wave packet achieves three-dimensional focusing. This autofocusing effect is believed to have potential applications such as material modification, plasma physics, nanoparticle manipulations, etc.