The 'drowning' group
These nouns refer to ways of dying or being killed. Accident and firing squad are count nouns.
by accident by cancer by crucifixion by drowning by electrocution by fire by firing squad by hanging by heart attack by lethal gas by lethal injection by misadventure by natural causes by poisoning by starvation by stoning by strangulation by suffocation by suicide
Her postmortem indicated death by drowning under the influence of drugs.
The former President and at least a dozen of his ministers were executed by firing squad.