Prince George’s police made 551 arrests, took 54 guns off the streets and seized more than $400,000 worth of drugs during a special effort to tamp down on January violence, authorities said at a news conference Wednesday.

The effort — initiated in part because Prince George’s saw 15 murders and a justified fatal shooting in January 2011 — took narcotics, pawn and other specialized officers from their regular duties and re-assigned them to work overnight hours in some of Prince George’s most dangerous areas inside the Capital Beltway, authorities said. Maj. Joe McCann, who led the effort, said he believes the officers helped drive crime down, noting that this January, detectives investigated just six homicides.

“You see a changing in the crime culture,” McCann said.

Police officials said they are still tabulating the total cost of the operation, which ran from Jan. 1 to Feb. 4 and required officers to be paid some overtime. Prince George’s Police Chief Mark Magaw said that while he still believes last January’s spate of murders was a fluke, he thinks this year’s initiative alleviates the pressure that police and elected officials felt at the beginning of last year.

“We were committed and determined not to have the same January we had in 2011,” he said.