The U.S. Department of Justice has opened a federal civil rights investigation into the fatal shooting of 18-year-old Michael Brown.

In a joint statement released by U.S. Attorney Richard Callahan, Acting Assistant Attorney General for the Civil Rights Division Molly J. Moran and FBI SAC William Woods say the investigation was launched at the request of Attorney General Eric Holder.

Brown was shot by a Ferguson police officer Saturday. Police say he struggled with police for an officer’s gun prior to the shooting, but witnesses say he was fleeing and had his hands up when he was shot. The incident has prompted riots, looting and property damage.

The statement says while looking into whether federal civil rights violations occurred, they will work, “as much as possible with the local authorities who are determining whether there were any state law violations.”

The St. Louis County Police and FBI are already conducting parallel investigations of the incident.

The statement says, “While the investigation will be handled as expeditiously as possible, our pledge to the community is that it will be a thorough and complete investigation, following the facts wherever they may take us.”

Witnesses are urged to contact the St. Louis office of the FBI at (314) 589-2500.