An unmanned Antares rocket exploded seconds after lift off from a commercial launch pad in Virginia on Tuesday, a NASA TV broadcast showed. The 14-story rocket, built and launched by Orbital Sciences Corp, bolted off its seaside launch pad at the Wallops Flight Facility at 6:22 p.m. EDT/2222 GMT carrying a Cygnus cargo ship for the International Space Station. The cause of the accident was not immediately known, said NASA mission commentator Dan Huot. NASA said there were no injuries.