The Mufti Shaykh ‘Abdul-‘Azīz Āl ash-Shaykh:

Causing corruption in the land by way of highway robbery, terrorizing the people, bombings, explosions, or hijacking planes, ships, and trains are from the major sins. The recompense for one who commits this crime is that he is either executed, imprisoned, or his limbs are cut off on opposite sides. Then, a more severe punishment will come from Allāh on the Day of judgment.