Updated

Protesters are promising their biggest march yet a day after the Baltimore Police Department acknowledged that it failed to get Freddie Gray the medical attention he needed after his arrest.

Protesters vowed to "shut down" the city Saturday by marching through the streets and snarling traffic.

The president of a black lawyers' group predicted thousands of people would turn out for the demonstration, when good weather is forecast and the Baltimore Orioles host the Boston Red Sox.

Malik Shabazz of Black Lawyers for Justice has demanded the arrest of six officers involved in the arrest of Gray, who died Sunday a week after suffering a spinal injury while in police custody.

The officers are suspended with pay and under criminal investigation by their own department.