DETROIT—An officer who works for Wayne State University in Detroit was shot while on duty Saturday evening near the campus and was in “critical” condition, the city’s police chief said.

The officer, a five-year veteran, was on patrol when he radioed, saying he was investigating possible thefts of navigation systems from cars and SUVs, and was about to speak to someone apparently on a bike, James Craig said.

“It was boom, boom, boom,” Jacob Bolton, 20, who lives nearby, said in an interview later. “I heard some gunshots and I heard somebody hollering. But at first I thought I was dreaming.”

Officers who arrived on the scene found the officer injured on the ground, Craig said.

Shortly after the shooting, which occurred around 6:30 p.m., several dozen armed officers were seen in the residential area of Woodbridge within two blocks of the campus.

“A massive manhunt is going on” with local, state and federal authorities, Craig said.

Police are searching for an African-American man in his 40s with a full beard, a university statement posted on the school’s website said Tuesday night. It added he was wearing a white T-shirt with white and black lettering, a skull cap and a brown jacket.

Wayne State has more than 27,000 students and is located in the heart of Detroit.

Craig cited four recent incidents around the country in which law enforcement officers were shot.

The shootings of police officers in Texas and Missouri on Sunday were the latest in what law enforcement officials say is an alarming spike in ambush-style attacks. A San Antonio detective was fatally shot, and a St. Louis officer was shot twice in the face but survived.

Police officers were also shot and injured during traffic stops in Sanibel, Fla., and Gladstone, Mo., on Sunday night, but authorities have not suggested those were targeted attacks.

One-third of police officers shot to death on the job this year were purposely targeted by their assailant, according to the National Law Enforcement Officers Memorial Fund.