The Washington Post is tracking such killings across America because local police departments are not required to file reports to the federal government, meaning that nationwide statistics are incomplete or unavailable.
The Post found that so far this year, at least 385 people have been shot and killed by police across the United States -- a rate of more than two a day.
The rate is far higher than that tallied over the past decade by the federal government, which must rely on partial data because of the voluntary reporting requirements.
In one case, for instance, police in the Florida city of Miami Gardens killed a schizophrenic man who was waving a broomstick. His mother had called police because she couldn't persuade him to come in from the cold.
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Still, the Post noted, most of those killed this year were armed with potentially lethal objects -- mainly guns, but also knives and other items.
Sixteen per cent were carrying a toy or were unarmed.
The tally comes as a national debate is taking place about the level at which police use deadly violence, especially in black and Latino communities.
The death and subsequent lack of legal action against the police officer who shot him prompted widespread riots in the St Louis suburb.
In Baltimore last month, riots broke out following protests over the death of Freddie Gray, 25, who died from injuries sustained in the back of a police van.
The Post found that overall, blacks were killed at three times the rate of whites or other minorities in the police killings it analyzed this year.