Srila Visvanatha Cakravarti Thakura explains that Indra, not Vrtrasura, was actually killed. He says that when Vrtrasura swallowed King Indra and his carrier, the elephant, he thought, Now I have killed Indra, and therefore there is no more need of fighting. Now let me return home, back to Godhead. Thus he stopped all his bodily activities and became situated in trance. Taking advantage of the silence of Vrtrasuras body, Indra pierced the demons abdomen, and because of Vrtrasuras trance, Indra was able to come out. Now, Vrtrasura was in yoga-samadhi, and therefore although King Indra wanted to cut his throat, the demon's neck was so stiff that Indra's thunderbolt took 360 days to cut it to pieces. Actually it was the body left by Vrtrasura that was cut to pieces by Indra; Vrtrasura himself was not killed. In his original consciousness, Vrtrasura returned home, back to Godhead, to become an associate of Lord Sankarsana. Here the word alokam means the transcendental world, Vaikunthaloka, where Sankarsana eternally resides.