A report issued by the National Law Enforcement Officers Memorial Fund on Tuesday indicated that police officer gun deaths were up by 56 per cent this year.

In 2013, some 102 police officers were killed by firearms while on duty. This year, 126 were killed.

The gun deaths in 2013 were at their lowest since the 19th century, and this year's killings include those related to elevated racial tensions following civilian killings at the hand of police officers.

An unarmed black teenager, Michael Brown, was shot and killed by Ferguson, Missouri officer Darren Wilson in August, leading to nationwide protests and rioting. This month, NYPD officers Rafael Ramos and Wenjian Liu were killed by a black man, Ismaaiyl Brinsley. Before the murders, Brinsley posted messages on his Instagram account indicating he would kill police officers. He killed himself after the murders.

The number of ambush assaults on police officers rose to 15 this year from just five in 2013. However, there were also 15 ambush assaults reported in 2012.

On Sunday night, two gunmen opened fire on two LAPD officers in South Los Angeles in an ambush attack. No one was injured, and one suspect has been arrested. National Law Enforcement Officers Memorial Fund CEO and Chairman Craig Floyd called the increased attacks on police officers disturbing.

"With the increasing number of ambush-style attacks against our officers, I am 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," he said in a statement.

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

The most officer deaths occurred in California with 14 killings in 2014. Texas followed with 11, while New York, Florida, and Georgia had nine, six, and five, respectively.