WASHINGTON — Roughly once a week, 390 times over the past eight years, Philadelphia police officers opened fire at a suspect. The shootings involved 454 officers, most of them on patrol. Almost always, the suspects were black. Often, the officers were, too.

Fifty-nine suspects were unarmed. Officers frequently said they thought the men — and they were almost always men — were reaching for a weapon, when they were actually doing something like holding a cellphone.

The statistics were laid out in a Justice Department report on Monday, which does not allege racial discrimination but offers an unusually deep look at the use of lethal force inside a major city police department, including information on the race of officers and suspects. It is the kind of data that has been nearly absent from the debate over police tactics that began last summer with a deadly shooting in Ferguson, Mo.

Only a handful of major departments regularly publish statistics on police shootings, and those that do are not always consistent. That makes comparing the records of police departments difficult. But even with such spotty figures, Philadelphia stands out when compared with the public data in other cities like New York, Los Angeles and Chicago. In many years, Philadelphia saw more police shootings than New York, a city with five times the number of residents and officers.