In natural disasters: died or killed?

Solution 1:

kill, verb: To put to death; to deprive of life. The Black Death was a disease that killed millions.

You can be killed by an earthquake, by a building collapse, by drowning, or by a heart attack. Intent and purpose have nothing to do with it. Anything that causes you to die is something that kills you. Haven't you heard the warning, "Smoking kills"?

The only difference I can think of between "to die" and "to be killed" is that the latter carries a connotation that the death was somehow violent or unnatural.

"My grandfather was killed by old age! In his sleep!" (??)

Solution 2:

Either everyone died or everyone was killed works pretty much equally well:

• Earth was destroyed this morning: everyone died in a parallel universe.
• Earth was destroyed this morning: everyone was killed in a parallel universe.

However, got killed sounds informal, so you probably wouldn’t use it in formal writing except as related speech.