UPDATE: Police search for suspects after Ferguson "ambush"
An officer from the St. Louis suburb of Webster Groves, 32 and a seven-year veteran, was shot in the face. The bullet entered under his right eye and lodged behind his ear, Belmar said.
The other officer, from the county police force, was shot in the shoulder, and the bullet came out his back, Belmar said. That officer is 41 years old and a 14-year veteran. Police did not immediately name either officer.
In a statement, Attorney General Eric Holder called the shootings "inexcusable and repugnant."
"Such senseless acts of violence threaten the very reforms that nonviolent protesters in Ferguson and around the country have been working towards for the past several months," he said.
Gov. Jay Nixon encouraged anyone with information to come forward, and offered his prayers to "these brave officers and their families."
A Justice Department report last week alleged widespread racial bias in law enforcement in Ferguson. The report was commissioned after the fatal shooting of Michael Brown, an unarmed black teenager, by a white police officer in August.
Brown's parents released a statement on Thursday condemning the shootings of the officers.
Belmar said that police were taking care to respect the First Amendment rights of protesters. But he wondered what might have happened if the shooter or shooters had been much closer, "a threat right there in front of you that can be engaged."
"This is beginning at times to be very difficult for any law enforcement agency anywhere to really wrap their arms around," he said.