The Congressional Black Caucus is calling on Attorney General Jeff Sessions and the FBI to help in the search for missing black girls in the Washington, D.C., area, following an alarming string of missing children cases from the nation's capital.

The District of Columbia logged 501 cases of missing juveniles, many of them black or Latino, in the first three months of this year, according to the Metropolitan Police Department, the city's police force. Twenty-two were unsolved as of March 22, police said.

The letter, dated Tuesday and obtained Thursday by The Associated Press, was sent by Congressional Black Caucus chairman Cedric Richmond, D-La., and Del. Eleanor Holmes Norton, who represents the District in Congress.

They called on Sessions and FBI Director James Comey to "devote the resources necessary to determinelittle media attention. That's deeply disturbing," Richmond's letter said.

Derrica Wilson, co-founder of the Black and Missing Foundation, said that despite the assurances from police, it was alarming for so many children to go missing around the same time.

On Tuesday night, she noted, her group had four reports of missing children and only one had been found.

"We can't focus on the numbers. If we have one missing child, that's one too many," Wilson said.

Wilson said she is concerned about whether human trafficking is a factor, citing the case of 8-year-old Relisha Rudd, who has been missing since she vanished from a city homeless shelter in 2014.

A janitor who worked at the shelter was found dead of apparent suicide during the search for the girl.

"They prey on the homeless, they