At least 385 people have been shot and killed by police in the United States during the first five months of this year, more than two a day, according to a Washington Post analysis.
That is more than twice the rate of fatal killings tallied by the federal government over the past decade, a count officials concede is incomplete.
"These shootings are grossly under-reported," said Jim Bueermann, a former police chief and president of the Washington-based Police Foundation, a non-profit body dedicated to improving law enforcement.
"We are never going to reduce the number of police shootings if we don't begin to accurately track this information."
A national debate is raging about police use of deadly force, especially against minorities. To understand why and how often these shootings occur, the Post is compiling a database of every fatal shooting by police in 2015, as well as of every officer killed by gunfire in the line of duty.
It looked only at shootings, not killings by other means, such as stun guns and deaths in police custody.
About half the victims were white, half minority. But the demographics shifted sharply among the unarmed victims, two-thirds of whom were black or Hispanic.
Overall, blacks were killed at three times the rate of whites or other minorities when adjusting by the Census-recorded population where the shootings occurred.
Most victims - more than 80 per cent - were armed with potentially lethal objects, primarily guns, but also knives, machetes, revving vehicles and, in one case, a nail gun.
Forty-nine people had no weapon, while the guns wielded by 13 others turned out to be toys.
The dead ranged in age from 16 to 83. Eight were younger than 18.
About half of the time, police were responding to people seeking help with domestic disturbances and other complex social situations.
Nearly a quarter of victims, 92, were identified as mentally ill.
- additional reporting Bloomberg