Apollo 1 - Accident or Alien Attack?

Space traveling can be dangerous! 

 Apollo 1 is the subsequent term for the planned first manned space mission in the Apollo program, NASA. During a test on the launch pad at the 27th January 1967 a fire broke out in the capsule, in which three astronauts were killed. The flight crew of three members with the new Apollo spacecraft in low Earth orbit was not performed. The American moon landing program was set back by far. Arrived as the tower personnel without proper respiratory protection to the capsule, the area was already filled with smoke heavily. Be interrupted during the work on the capsule, the work often had to take to the air. As was the hatch opened at 18:36 clock could no signs of life on the astronauts are more conspicuous, they were probably suffocated already 30 seconds after the fire broke out. The fire was extinguished in the capsule by itself, the tower personnel put out only small pockets of fire on the tower itself, although the fire was extinguished when the fire brigade arrives, it was feared that the fire rescue rocket (LES) of the missile by the heat might have. At 18:40, an attempt was made ​​to White to get out of his seat. Against 18:45 clock the death of the astronauts was determined by a physician. Only with the delay could be recovered bodies from the capsule, which lasted about 90 minutes. The bodies, suits and seats were partially fused with each other strongly.

Were aliens the cause of this tragedy ?