(CNN) Baltimore's mayor on Friday ousted city Police Commissioner Kevin Davis in favor of one of his deputies, saying the city wasn't reducing violence fast enough amid a soaring homicide rate.

Mayor Catherine Pugh elevated Deputy Commissioner Darryl D. DeSousa , saying she'd tried to work hand-in-hand with Davis during her 13 months in office but needed to see more progress.

DeSousa said one of his first initiatives is to temporarily put more officers on the streets -- largely by transferring administrative officers and detectives to patrol duties -- and to place them in "strategic locations," such as areas near "problematic businesses."

His promotion comes after Baltimore tallied more than 340 homicides in 2017 -- the highest yearly number on record there in more than two decades.

"I'm impatient," Pugh said in a news conference Friday morning. "We need violence reduction. We need the numbers to go down faster than they are."

"This commissioner (Davis) worked hard, but I'm looking for new ... ways to change what we're seeing here every day," she said. "I need my police department to give me creative ideas."

The firing of Davis, who was promoted from deputy to commissioner in 2015 amid a public uproar over the death in police custody of city resident Freddie Gray , shakes up a department that has seen its share of recent challenges.

That includes the homicide rate, as well as a 2016 Justice Department report that found Baltimore police had long engaged in racial bias against African-Americans.

New commissioner: We're coming for 'the trigger-pullers'

DeSousa said his surge of officers on the streets began Friday and "was in the works several weeks ago." Similar surges happened in August and September, he said.

Commanders will evaluate which administrative officers and detectives will join this surge, but some "detectives are (already) on the streets," he said.

DeSousa didn't say how many more officers would be on patrol, and he at one point declined to say how long this surge would last, other than that it would go "for a while."

He also said the current increase was deliberately timed to coincide with the first anniversary of a 13-day stretch -- January 19 through 31, 2017 -- during which the city had an "unacceptable" count of 18 homicides and 40 nonfatal shootings.

"I think that this initiative during this next 13-day period is going to be very effective," he said.

DeSousa said his main priorities were to reduce violence and crack down on violent, repeat offenders.

"I have a real strong message for the trigger-pullers: We're coming after them," he said. "It's going to be (an) accelerated pace. The district commanders in all nine districts know who they are. And we're coming after them."

DeSousa, 53, has served in every rank with Baltimore police since he started there in 1988, he said, and had been Davis' deputy commissioner for the patrol bureau since August 2015.

Asked how his efforts would differ from Davis', he pointed to the initiatives like the patrol surge and said efforts to reduce violence were "going to be accelerated."

Davis couldn't immediately be reached for comment.

Mayor deflects question on firing and detective's death

A reporter asked Pugh during Friday's news conference whether Davis' firing had anything to do with the unsolved killing of Baltimore homicide detective Sean Suiter.

Suiter, 43, was shot in the head with his own gun after struggling with his killer on November 15 in west Baltimore, police said. The 18-year department veteran had been investigating a killing when he noticed a man acting suspiciously and ran toward him, investigators said.

Suiter's death came the day before he was scheduled to testify before a grand jury in the case of several Baltimore police officers accused of seizing money from people they have stopped, claiming fraudulent overtime and filing false affidavits.

Pugh, responding to the reporter's question, reiterated that her decision to replace Davis had to do with overall violence in the city.

"My decision is because I'm impatient," Pugh said. "My decision is based on the fact that we need to get these numbers down."

Union leader supports new commissioner

The leader of a Baltimore police officers' union said Friday he welcomed DeSousa's promotion, and that he believes the new commissioner will bring positive change.

"He knows the city and he knows how it works. He knows what needs to be done," said Gene Ryan, president of Baltimore City Fraternal Order of Police Lodge 3.

"He is very capable, and we look forward to working with him."

Ryan said the outgoing commissioner "did the best he could do."

"It's a hard job. He wasn't getting it done, so the mayor wanted to replace him. ... She had to consider the best situation for the city and the police department."

Davis took charge amid Freddie Gray protests

Davis, the outgoing commissioner, was promoted in July 2015 by then-Mayor Stephanie Rawlings-Blake amid the outcry over Gray's death.

Three months earlier, Baltimore police had arrested Gray, a 25-year-old black man, after officers found him with a knife in his pocket. Gray died after suffering a neck injury while being transported in a police van.

A Baltimore grand jury indicted six police officers on a range of charges, including involuntary manslaughter and reckless endangerment. But after three officers were acquitted, charges against the others were dropped. Baltimore officials in September 2015 approved a $6.4 million settlement with Gray's family for all civil claims tied to his death.

Rawlings-Blake promoted Davis, ousting then-Commissioner Anthony Batts, amid anger over the department's handling of protests over Gray's death. The city's police union had said in a report that the riots were preventable and fueled by the "passive stance" adopted by Batts and top commanders.

Pugh took office in December 2016.

"Baltimore City is singularly focused on violence reduction," she said then. "Improving quality of life through economic progress, health and wellness, and youth development reduces violence in communities, as evidenced by the success of other cities that have tackled increases in violent crime."