Four journalists arrested during last summer's protests over the Ferguson shooting death of Michael Brown are suing St. Louis County's police department for civil rights violations and unlawful detention.

The lawsuit filed Monday in St. Louis also names 20 unidentified St. Louis County officers.

Plaintiffs include two journalists who were covering last August's protests for German publications, as well as a freelance reporter and a journalist for an online investigative publication. The suit describes them as U.S. citizens.

The lawsuit alleges that the journalists' arrests for failing to disperse when ordered by police was unjustified and was an infringement of constitutionally protected freedom of the press.

A St. Louis County police spokesmen referred questions Monday to the county counselor, who did not immediately return a message seeking comment.