They both mean the same thing, but only because your statement starts with "Thank God". By starting with that exclamation, every native English speaking person would assume that there was some kind of accident, terroist act, criminal act, natural disaster, etc., that often results in someone's death. In this usage, "killed" means to unexpectedly die by other than a natural cause of death (sickness, disease, or old age). Also, because you use "no one" it implies that multiple people could have died from whatever the event was. That also would not be a natural cause of death, hence killed.

No...

Well... the fact that someone died, it doesn't mean that he was killed... the equality of these statements depends on the situation.

Yes. They both mean the same thing.