People are blocking streets around Oakland police headquarters after chaining themselves to the front of the building to protest recent grand jury decisions not to indict white officers who killed unarmed black men in Ferguson, Missouri and New York.

Television news footage shows more than a dozen people holding hands and blocking two roads off Interstate 880 in downtown Oakland near the police building Monday morning. The Oakland Tribune reports that more than 50 protesters earlier tried to prevent access to the police headquarters. Some of the protesters had chained themselves to the front doors and a flagpole.

It was not immediately clear whether there were any arrests. Oakland police spokeswoman Johnna Watson said she was checking on the protest.