Baltimore Mayor Kevin Davis on Friday, citing the need to get a handle on the city's record levels of violence.
Deputy Commissioner Darryl D. DeSousa, the top commander in the police department's patrol bureau, will take Davis' place, effectively immediately.
Pugh said his appointment will be eventually made permanent.
After 2017 ended with 343 homicides — near an all-time high — the mayor said she decided a change of police leadership was necessary.
"As I have made clear, reducing violence and restoring the confidence of our citizens in their police officers is my highest priority," Pugh said in a statement. "The fact is, we are not achieving the pace of progress that our residents have every right to expect in the weeks since we ended what was nearly a record year for homicides in the city of Baltimore."
The rise in violence that was in its early stages when Davis took over the police department has not dropped off, with 342 homicides in 2015, 318 in 2016 and 343 last year — a record per-capita for the city.
Pugh said her decision to replace Davis was made because she is "impatient" in relation to the need to reduce homicides, but was "not done under a cloud." She said Davis "worked hard," but she wants more creativity and innovation from her police commissioner.
Pugh said she has asked DeSousa to be "creative" in reducing homicides and other crime.
"Crime is now spilling out all over the city, and we've got to focus, so I am charging this commissioner and his staff to get on top of it to reduce the numbers and to reduce them quickly," she said.
Davis could not immediately be reached for comment. Other top commanders declined to comment. The decision appeared to come as a surprise to many in the department.
DeSousa, at a morning news conference with Pugh, said he "has a lot of respect" for Davis and wishes him well. He also said he knows city residents are "frustrated and they want answers and they want change, and it's going to happen."
He said a new initiative, in the works for weeks, began Friday morning to send a "surplus of officers" in waves to target hot spots, major traffic corridors and "violent repeat offenders" in order to drive down violence
"I have a real strong message for the trigger-pullers, and it's we're coming after them," he said. "It's going to be at an accelerated pace."
He said the initiative is going to "last a while," but he did not provide additional details. He said he is "a chess player" who has always been focused on the operational side of policing. "I don't like to be outwitted."
Pugh said she informed Davis of her decision Friday morning.
In a recent interview with the Baltimore Sun, Davis acknowledged widespread problems in the department, but said progress was being made and was not getting enough attention.
"The whole notion that accountability is not underway is crap," Davis said. He also said the department he has led since July 2015 has a "culture that looks at accountability as a four-letter word."
"This is a dysfunctional police department," Davis said. "I'm telling you as a person who has seen what a healthy organization looks like. This is not one of them. But we're making huge strides in getting there."
Davis' tenure has been partially defined by scandals — including the indictment last year of eight officers on federal racketeering charges — though not as much as the violence and the city's consent decree with the U.S. Department of Justice, which mandates sweeping reforms.
The city entered into the deal last year, after a review by the Justice Department found widespread discriminatory and unconstitutional policing in the department, following street protests in 2015. Davis has been a champion of the process, saying reforms are deeply needed in the department.
Davis was named interim commissioner by former Mayor Stephanie Rawlings-Blake in July 2015 after she fired his predecessor, Anthony Batts, amid a surge in violence following rioting and unrest in the city that April. That turmoil erupted after 25-year-old Freddie Gray died from injuries suffered while in police custody.