ST. LOUIS (AP) -- A suburban St. Louis police officer was "ambushed" during a traffic stop Friday and shot at least once, wounding him critically, authorities said.
The suspect in custody is a man in his 30s and likely will be charged in the shooting, St. Louis County Police Chief Jon Belmar said at a news conference. Authorities did not provide the race or identity of the officer or the suspect.
Ballwin Police Chief Kevin Scott described the shooting, saying that the officer was walking back to his car after the initial conversation during the traffic stop when the motorist followed him and fired at least three shots. The shooting was captured on video, he said.
"Make no mistake: We believe during this investigation that Ballwin officer was ambushed, period," Belmar said. "It's an unfortunate state of events we're dealing with right now."
Scott said the shooting, which happened hours after five officers were killed and seven were wounded in Dallas during a protest, is being investigated and that the officer had no opportunity to pull his service revolver, saying he "was completely helpless at this point."
"I don't know about the motive at this point at all, "Scott added.
Belmar told KMOV-TV earlier that a gun was recovered at the scene, though it wasn't clear to whom it belonged.
Scott says the officer, who has not been identified, has been one for nine years, two of which with the Ballwin department.
The suspect was on probation for a weapons violation in St. Louis, Belmar said, had been on probation for a stolen vehicle in Oklahoma and was picked up for a firearm violation in California. He was paroled in 2015.
Missouri Gov. Jay Nixon's spokeswoman Channing Grate said he would not leave for an eight-day overseas trade mission Friday as planned and instead would return to Missouri from an event in Philadelphia. Nixon said he was concerned about recent events, including the fatal Dallas police shootings and the shooting of the Ballwin officer.
The west St. Louis County police force in 30,000-resident Ballwin has 51 commissioned officers and "will serve the community through professional conduct at all times without prejudice or bias," according to the department's website.
Three times since 2005, the suburb, which is roughly 90 percent white, has been named by Money magazine as among the nation's 100 best places to live due to, among other things, its low crime rate.