Other source:

Sensing he’s in a losing battle, King Piccolo resorts to a cowardly resort, threatening to kill Tien, if Goku moves a muscle. Yamcha reaches the place and lands his plane. Yajirobe has also arrived to watch Goku fight hesitating whether he should or shouldn’t. Upon discovering that King Piccolo killed Shenron, Goku resigns himself to endure repetitive pains getting his limbs crippled. With Goku incapacitated, King Piccolo prepares to finish him off, but Goku uses full power in his right fist to punch a hole through King Piccolo’s torso. Seconds before King Piccolo’s death he uses the last of his energy to create his final offspring. Yajirobe saves Goku from falling to his death and retrieves Tien. Tien is motivated to train better than ever.