Members of Congress have written the federal Justice Department to assist local police in locating the large number of missing children in the nation’s capital.

The letter, obtained Thursday by The Associated Press, was sent by Congressional Black Caucus chairman Cedric Richmond, D-La., and Delegate Eleanor Holmes Norton, who represents the District in Congress. They called on Attorney General Jeff Sessions and FBI Director James Comey to “devote the resources necessary to determine whether these developments are an anomaly or whether they are indicative of an underlying trend that must be addressed.”

“Ten children of color went missing in our nation’s capital in a period of two weeks and at first garnered very little media attention. That’s deeply disturbing,” Richmond’s letter said.

The plea comes amid an increase in attention on missing children of color across the country.

DC Police told the AP that there has been no increase in missing children cases this year, though the number — 501 cases this year alone — is staggeringly high. Twenty-two of those cases remain unsolved.

The National Crime Information Center says there are 170,899 missing black children under 18 in the United States, more than any other category except for the white/Hispanic combined number of 264,443. Both numbers increased from the year before, which saw 169,655 missing black children and 262,177 missing white/Hispanic children.