The U.S. Justice Department announced this week that it is conducting a federal probe into the shooting death of African-American teenager Michael Brown at the hands of police in Missouri.

"The shooting incident in Ferguson, Missouri this weekend deserves a fulsome review. In addition to the local investigation already underway, FBI agents from the St. Louis field office, working together with attorneys from the Justice Department's Civil Rights Division and US Attorney's Office, have opened a concurrent, federal inquiry," said Attorney General Eric Holder.

Holder added, "The federal investigation will supplement, rather than supplant, the inquiry by local authorities. At every step, we will work with the local investigators, who should be prepared to complete a thorough, fair investigation in their own right. I will continue to receive regular updates on this matter in the coming days. Aggressively pursuing investigations such as this is critical for preserving trust between law enforcement and the communities they serve."

Several black lawmakers wrote to the Justice Department to expand the investigation. Brown's killing "may be part of a continuing pattern of the use of deadly force by police against unarmed African-Americans," wrote Rep. Marcia Fudge (D-Ohio), the head of the Congressional Black Caucus, and Reps. Lacy Clay (D-Mo.) and John Conyers (D-Mich.)," according to The Hill.

Brown, who was going to start college this week, was shot on Saturday after a confrontation with an officer. Both the police department and eyewitnesses agree that the officer pulled up alongside Brown as he walked on the sidewalk, but there are conflicting accounts about what happened next, according to The St. Louis Dispatch.

St. Louis County Police Chief Jon Belmar said Brown "physically assaulted" the officer, pushing him back into his car and trying to take his weapon.

"There was at least one shot fired within the car. After that the officer went back, came back out of the car, he exited his vehicle, and there was a shooting that occurred where the officer in fact shot the subject, and ... they were fatal injuries," Belmar said.

St. Louis County is investigating the shooting, and the FBI has launched a civil rights investigation.

There have been protests and rallies since Saturday. Hundreds turned up for a vigil at the shooting site on Saturday. A hundred people protested outside the police precinct, and police responded in riot gear and brought dogs. Looting incidents took place on Sunday and Monday, with police using tear gas and rubber and wooden bullets.

Ferguson police chief said Tuesday he is holding off on publicly identifying the officer who fatally shot the teenager because of death threats, according to reports. The officer was placed on administrative leave on Saturday.

On social media, moments of silence to honor victims of police brutality are being organized nationally on Aug. 14 at 7 p.m. under the hashtag #NMOS14 and at https://www.facebook.com/NMOS2014. So far, 54 vigils in 30 states are listed, including: Colorado (Denver); Georgia (Valdosta); Nevada (Carson City); New Jersey (Wyckoff); Ohio (Cleveland); Rhode Island (Providence); Tennessee (Memphis); and Utah (Salt Lake City).