Gov. Jay Nixon (D). (AP Photo/The St. Joseph News-Press, Sait Serkan Gurbuz)

Several Missouri elected officials called Monday for a "transparent" investigation into the death of Michael Brown, an unarmed black teenager who was fatally shot by a police officer in a St. Louis suburb on Saturday.

Gov. Jay Nixon (D) and the state's two U.S. senators emphasized the importance of gathering evidence in the case openly and without any bias. The FBI has opened an investigation.

"It is vital that the facts about this case are gathered in a thorough, transparent and impartial manner, in which the public has complete confidence," Nixon, who asked the U.S. Justice Department to probe the incident, said in a statement. "Our thoughts and prayers go out to all those affected by this tragic event, and I ask St. Louis County residents to exercise patience and respect for their neighbors as federal authorities work to get to the bottom of what happened through this comprehensive, independent review."

Brown's death sparked rioting in the city of Ferguson on Sunday evening. According to the Associated Press, St. Louis County Police Chief Jon Belmar said Brown and another man were involved in a fracas with a police officer before he was shot. Authorities are still gathering details of what transpired.

One of the earliest to issue a statement responding to the shooting was Sen. Claire McCaskill (D), who demanded a thorough accounting of the events that led to the teenager's death.

“As a mother, I grieve for this child and his family. I pray that the wonderful, hardworking, and God-loving people of Ferguson will find peace and patience as we wait for the results of what will be numerous and thorough investigations of what happened," said McCaskill. "I, like so many other Missourians, will not be satisfied until we have a complete and transparent understanding of all the facts and circumstances that led to this young man’s death."

Sen. Roy Blunt (R) sounded a similar note.

“I join all Missourians in remembering the family of Michael Brown and the Ferguson community as they grieve the tragic loss of this young man. His recent high school graduation should have been a beginning of better things," Blunt said in a statement. "Everyone deserves a transparent understanding of what happened here. I am fully supportive of County Executive Charlie Dooley and St. Louis County Police Chief Jon Belmar calling for DOJ and the FBI to take a careful, open review of the events that led to this tragedy for everyone involved.”

Rep. Ann Wagner (R) said, "As a mother of three children, I cannot even imagine the pain of losing a child.  My thoughts and prayers go out to Michael Brown’s family and to the people of Ferguson as they deal with this tragic loss. As we search for answers together, we must remain calm and compassionate while truth and justice are served."