Watch Hayley's report on locking up kids
Thousands of children are being locked up in prison cells in England and Wales every year, says a new report.
Police in England and Wales are allowed to put kids behind bars, as long as they're at least 10 years old.
But one charity thinks this is wrong and should be stopped. Frances Crook from the Howard League said: "A police cell is not a safe place for a child."
The police say officers think carefully before putting a kid behind bars and it's often done for their own safety.
In Greater Manchester, more than 16,000 kids under the age of 16 were detained in just one year. Many of them haven't done anything serious.
Frances Crook added: "[Police cells] are designed for adults, they don't have the facilities to deal with children and it is very frightening for children."