"The recent acts of violence will not be tolerated in a community that has worked so tirelessly over the last year to rebuild and become stronger," St. Louis County Executive Steve Stenger said in a statement. "The time and investment in Ferguson and Dellwood will not be destroyed by a few that wish to violate the rights of others."
"We are deeply disappointed with the violence that took place last night," Ferguson Mayor James Knowles III said in a statement today. "This kind of behavior from those who want to cause disruption and destroy the progress from this past year will not be tolerated. We are asking for our citizens and businesses to be diligent and to be watchful for those who want to cause harm to our community."
Knowles added, "We are asking for peace as we strive to once again become a community of choice for everyone."
The state of emergency follows an outbreak of violence in Ferguson, including a police-involved shooting Sunday night that left a suspect in critical condition.
Two teenagers were also shot early Monday morning, as they walked on a sidewalk near the Michael Brown memorial. They were both hospitalized with non-life-threatening injuries, police said.
Sunday night's violence fell on the anniversary of the death of Michael Brown, an 18-year-old unarmed black teen who was shot and killed by Ferguson police officer Darren Wilson, on Aug. 9, 2014.
A grand jury did not indict Wilson, who resigned last November. The death of Brown sparked protests and touched off the national "Black Lives Matter" movement.
Earlier Sunday, before the violence, a march was held in Ferguson in Brown's honor.
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