Baltimore detective shot in head, 'cold, callous' gunman sought

A Baltimore homicide detective who was shot in the head Wednesday night was in “grave condition” on Thursday as cops launched a dragnet for the “cold, callous killer" who took aim at the 18-year police veteran.

The unidentified police officer was shot around 4:30 p.m. by a man who approached him while engaging in “suspicious behavior," FOX45 Baltimore reported. The shooting happened in a troubled area of Baltimore that is grappling with high crime rates.

Police officers respond to Bennett Place and N. Fremont Avenue after a call went out that an officer is shot Wednesday, Nov. 15, 2017, in Baltimore, M.D.  Baltimore police said in a tweet that one of their officers was shot Wednesday evening. The department did not immediately disclose the officer's name or any other details. (Kevin Richardson/The Baltimore Sun via AP)

A Baltimore homicide detective was shot in the head on Wednesday.  (AP)

Federal agencies increased their reward to $64,000 on Thursday for information leading to the gunman’s arrest.

The officer was on life support in the intensive care unit. Few details were revealed about the detective, but Police Commissioner Kevin Davis said the man has a wife and two children.

"We are doing everything we can to keep [the officer] stabilized and to take care of the injury to his brain," said Dr. Thomas Scalea, chief of the University of Maryland Medical Center's Shock Trauma Center.

Davis said the officer was “just doing his job” when he was ambushed, and Davis vowed to capture the shooter.

"This is a dangerous profession," Davis said. "This is a dangerous job. Police officers know that at any given time they could confront someone who wants to do them harm, and that's exactly what happened tonight. With this community, we’re going to identify him, we’re going to arrest him, and we’re going to ensure justice is done.”

The Baltimore Police Department tweeted earlier Wednesday: "Please say an extra prayer for the officer and the officer's family."

Police cordoned off streets in the West Baltimore area and a tactical unit combed alleyways as they searched for the gunman. Numerous cruisers responded and a police helicopter buzzed overhead, illuminating streets below with a searchlight. The neighborhood where the officer was shot has a number of vacant row houses and has been the scene of numerous shootings over the years.

Police officers respond to Bennett Place and N. Fremont Avenue after a call went out that an officer is shot Wednesday, Nov. 15, 2017, in Baltimore, M.D.  (Kevin Richardson/The Baltimore Sun via AP)

Police officers respond to Bennett Place and N. Fremont Avenue after a call went out that an officer is shot Wednesday.  (AP)

Wednesday's shooting comes amid a particularly violent period in Baltimore: So far this year, the city of less than 620,000 inhabitants has seen more than 300 homicides. Baltimore Mayor Catherine Pugh called for an end to the gun violence at a news conference, saying “enough is enough.”

"We are praying for peace in our streets," she said. "And I can say to you all again and again: Enough is enough. Crime has to come to an end in this city. This kind of violence cannot be tolerated."

The Associated Press contributed to this report.

Katherine Lam is a breaking and trending news digital producer for Fox News. Follow her on Twitter at @bykatherinelam