The casket of New York Police Department Officer Joseph Lemm is carried into St. Patrick's Cathedral for his funeral services in the Manhattan borough of New York, Dec. 30, 2015. Reuters

Since the beginning of 2016, 12 police officers across the United States have been killed in firearms-related incidents — a 200 percent increase over the same time period in 2015, according to the National Law Enforcement Officers Memorial Fund, which tracks the preliminary numbers of police fatalities.

Eighteen police officers in total died on duty between Jan. 1 and March 11, with firearm-related incidents being the most common cause of the deaths. While more officer fatalities were recorded during that same period in 2015 — 23 in total, according to the memorial fund — only four were from gun-related incidents.

A total of five officers have died so far in 2016 in traffic-related incidents, compared with 11 in the same time period last year. One officer died this year from “other causes,” compared with eight in the same time period in 2015.

One of the most recent firearm-related deaths was of Texas Police Officer David Hofer, who was killed at the beginning of March in a gunfight after moving to the Dallas area from New York City, CBS News reported. One case that gained even more attention was that of Police Officer Ashley Guindon of the Prince William County Police Department in Virginia, who was killed on her first shift on the job in February.

Guindon was responding to a domestic dispute between an Army sergeant and his wife. Sgt. Ronald Hamilton later admitted he shot and killed his wife and Guindon, and that he also shot two other officers who escaped the incident alive.

Five officers alone were killed in about a week’s time in early February, from California to Georgia. Colorado has seen the most fatalities this year among law enforcement, with three deaths, followed by Illinois and Maryland, with two each. Deaths have also been recorded in Mississippi, New Jersey, North Dakota and Ohio, among others.