A team of about 100 federal law enforcement agents arrived Friday in the St. Louis, Missouri, area over concern that the grand jury decision regarding the shooting of Michael Brown could spur an angry reaction from locals. The jury will decide whether white Ferguson Police Officer Darren Wilson should be indicted for the Aug. 9 shooting of the unarmed black teen.

Speaking to ABC News on Friday, President Barack Obama urged Ferguson town residents to keep any protests peaceful. The grand jury was still meeting on Friday, but a decision is expected soon.

“This is a country that allows everybody to express their views, allows them to peacefully assemble, to protest actions that they think are unjust,” the president said during his visit to Las Vegas, where he was touting his decision to defer deportations of millions of illegal immigrants.

“But using any event as an excuse for violence is contrary to rule of law and contrary to who we are,” Obama added.

On Thursday, the shooting victim’s father, Michael Brown Sr., appeared in a televised public service announcement to make a similar plea.

“No matter what the grand jury decides, I do not want my son’s death to be in vain,” Brown Sr. says in the video. “I want it to lead to incredible change, positive change, change that makes the St. Louis region better for everyone.”

The FBI opened a special intelligence center on Friday in St. Louis to coordinate any response to violence, including establishing a second emergency team.

Missouri Gov. Jay Nixon declared a state of emergency earlier this week and activated the National Guard to be prepared to respond if rioting occurs.