FBI Director James Comey, shown in September, said Wednesday that the lack of accurate information about police-involved shootings is ”embarrassing and ridiculous.” (Saul Loeb/AFP/Getty Images)

The lack of accurate information about police-involved shootings is roiling the nation’s law enforcement community, leaving officials unable to say whether high-profile killings are isolated events or part of an alarming trend, FBI Director James B. Comey said Wednesday.

Speaking to a private gathering of more than 100 politicians and top law enforcement officials, Comey expressed frustration that the federal government has no better data on police shootings than databases assembled this year by The Washington Post and the Guardian newspaper.

“It is unacceptable that The Washington Post and the Guardian newspaper from the U.K. are becoming the lead source of information about violent encounters between police and civilians. That is not good for anybody,” he said.

“You can get online today and figure out how many tickets were sold to ‘The Martian,’ which I saw this weekend. . . . The CDC can do the same with the flu,” he continued. “It’s ridiculous — it’s embarrassing and ridiculous — that we can’t talk about crime in the same way, especially in the high-stakes incidents when your officers have to use force.”

At least 62 people have been shot and killed by police across the United States within the past 30 days, according to Washington Post data.

Mayors, police chiefs and state attorneys general said the lack of data is contributing to a dangerous trend in which police officers spurn aggressive tactics for fear of becoming the next officer to be caught on camera in a compromising situation.

Chicago Mayor Rahm Emanuel (D) implored U.S. Attorney General Loretta E. Lynch to stand up publicly for police officers and show them that the nation’s top cop has their back.

“There’s no doubt Ferguson, Baltimore, New York, Cleveland, in my view, have put the genie out of the bottle,” Emanuel said, reciting a list of cities where police-involved fatalities have provoked civic unrest.

Although most officers do the right thing, authorities lack the data to prove it, said Emanuel, who served as President Obama’s first chief of staff. “Unless we deal with backing them up, the gang members know” police “are not putting their hands on them because they don’t want to be prosecuted, whether it be by public opinion or by the court.”

The Summit on Violent Crime Reduction was convened by the Justice Department at the Washington Plaza Hotel. Although Justice Department officials told attendees that the meeting would be closed to the news media, D.C. Mayor Muriel E. Bowser (D) listed it on her schedule as a public meeting, and a Post reporter entered with the mayor’s entourage.

The summit comes as law enforcement agencies across the nation are taking unprecedented steps to improve transparency and data collection, efforts that could bring new clarity to how often and under what circumstances police officers use deadly force.

In New York, state officials now require a special prosecutor to investigate any death at the hands of police. In Texas, lawmakers recently approved legislation requiring local police to report shootings by their officers. And in California, Attorney General Kamala Harris has released a searchable database containing a decade’s worth of information about deaths in police custody, as well as officers killed or injured in the line of duty.

“We have a system currently that is almost entirely reactive, a system influenced by anecdote and emotion,” said Harris, who has dubbed her database the “Open Justice” initiative. “The beautiful thing about numbers is that they don’t lie.”

In perhaps the most significant development, the Justice Department announced Monday that it, too, is keeping a database of deaths in police custody — the first effort by federal officials to assemble accurate information about such killings as they happen. Until now, federal officials have relied on local police to report officer-involved shootings, but reporting is voluntary and typically occurs months after the fact.

“The administration’s position has consistently been that we need to have national, consistent data,” Lynch said Monday. “We are working closely with law enforcement to develop national consistent standards for collecting this kind of information.”

Advocates for better information about police use of force say the usefulness of the federal database remains to be seen.

“There are all sorts of important bits of info that should be collected in a national data base of deaths involving the cops,” said David Klinger, a former police officer and professor at the University of Missouri, who has long advocated for better data. “If they get it right, good on them. If not, well
. . . ”

The FBI has for years collected information about people killed by police officers, but reporting is voluntary and only 3 percent of the nation’s 18,000 police departments comply. As a result, the data is virtually useless, Klinger and others say.

The Post’s database, for example, shows that 758 people have been shot and killed by police so far this year — nearly double the number recorded in a single year by the FBI.

The vast majority of those killed were armed with a deadly weapon. However, blacks represent a disproportionate percentage of those who were unarmed when they were killed, the database shows.

Justice Department officials said Monday that its Bureau of Justice Statistics is exploring new methods of gathering the data on deaths in custody, including mining rosters maintained independently by newspapers and community activists and then requesting additional information from police departments, medical examiners and state agencies.

“It’s important to have transparency around police killings, but also around police interactions,” Baltimore Mayor Stephanie Rawlings-Blake (D) said in response to a reporter’s question during a separate event at the National Press Club on Wednesday. Rawlings-Blake cited her city’s efforts to provide more police with body cameras.

Rawlings-Blake saw her city erupt into riots and looting in April after the funeral of Freddie Gray, a black man who suffered fatal injuries while being transported in a police van. Recalling a conversation with police officials this year, the Baltimore mayor said she told them that they must embrace new levels of transparency and reform.

“Change is coming. If you can’t see that, you’re blind,” she said. “There is a wave in our country that is unrelenting, that will hold officers accountable.”

Mark Berman and Sari Horwitz contributed to this report.