IN 2013, some of the year's biggest headlines involved cop killers.

There was MIT Police Officer Sean Collier, who authorities said was shot and killed by the Tsarnaev brothers after the Boston Marathon bombings in April.

There was Christopher Dorner's rampage across Southern California in February. Two of the four people he killed were cops.

Yet those tragedies would prove the exceptions in 2013, which may have been one of the safest years in modern history for American police.

According to a preliminary report by the National Law Enforcement Officers Memorial Fund released yesterday, 111 law-enforcement officers died in the line of duty in 2013, the lowest number since 1959.

Most of the deaths came in traffic accidents, said the nonprofit, which tracks law enforcement deaths and maintains the National Law Enforcement Officers Memorial in Washington.

The most dramatic number in the report might be the 33 officers killed by gunfire, the lowest since 1887. It's also a steep drop from two years ago, when 71 officers were shot and killed on the job in 2011.