Other source:
After a year of space travel, the two Saiyans, Vegeta and Nappa, arrive on Earth. To celebrate their arrival, Nappa completely destroys East City with an energy blast. Sensing their power, the Z Fighters mobilize for an attack. The Saiyans search for any large power levels with their scouters, and they head toward Piccolo and Gohan. Just when Krillin shows up to help, the Saiyans also arrive. Piccolo learns that he is a Namek, because Vegeta recognizes the green skin that is typical of Nameks. Yajirobe knows the threat as well, but instead of stopping them, he is posing as the leader of the earth's Special Forces to get food.
