Fifty U.S. law-enforcement officers were killed by guns in 2014, a figure that marks a 56 percent jump from previous years but still remains far below historic highs, The Associated Press reported.

The average number of officers who have died in gunfire since 2004 is 55, according to statistics compiled by the nonprofit National Law Enforcement Officers Memorial Fund. Last year, 32 such deaths were reported; in 2011, the number was 73 -- the highest in any year in the past decade.

In all, the fund's report found that 126 federal, local, tribal and territorial officers were killed in the line of duty in 2014; that number is up 24 percent jump from the previous year. After gunfire, the second most common cause of death were traffic-related: 49 officers died on the road.

Significantly up was the number of ambush assaults on police officers, which stood at 15, compared with just five in 2013.

Craig Floyd, the National Law Enforcement Officers Memorial Fund's CEO, noted he was "deeply concerned that a growing anti-government sentiment in America is influencing weak-minded individuals to launch violent assaults against the men and women working to enforce our laws and keep our nation safe."

"Enough is enough," Floyd said in a statement. "We need to tone down the rhetoric and rally in support of law enforcement and against lawlessness."

The most deadly states for law-enforcement officers were California, Florida, Georgia, New York and Texas, Reuters said. The attacks received particular attention when two New York City policemen were shot and killed on Dec. 20 as they sat in their squad car.

The deadly ambush deepened the rift between the New York Police Department and the city's mayor, Bill de Blasio.

Officers Wenjian Liu and Rafael Ramos were gunned down in their car by Ismaaiyl Brinsley, after Brinsley had made threatening posts online, according to NBC New York. After shooting the officers, the suspect ran into a subway station and killed himself.