ATLANTA - Two officers in a remote Alaska town were ambushed as they chatted on a street.

A California officer and deputy were killed by an arson suspect with a high-powered rifle as they tried to serve a warrant.

Two other officers doing anti-drug work were gunned down by men along a busy Arkansas highway.

These so-called cluster killings of more than one officer helped make 2010 a particularly deadly year for law enforcement. Deaths in the line of duty jumped 37 percent to about 160 from 117 the year before, according to numbers as of yesterday compiled by the Washington-based National Law Enforcement Officers Memorial Fund, a nonprofit that tracks police deaths.

There also was a spike in shooting deaths. Fifty-nine federal, state and local officers were killed by gunfire in 2010, a 20 percent jump from last year's figures, when 49 were killed. The total does not include the death of a Georgia state trooper shot twice in the face Monday night in Atlanta as he tried to make a traffic stop.

And 73 officers died in traffic incidents; 51 were killed in 2009, according to the data.

Last year's toll of 117 officers killed was a 50-year low that encouraged police groups. But this year's total is more the norm than an anomaly: The number of police deaths has topped 160 five times since 2000, including 240 in 2001. The annual toll routinely topped 200 in the 1970s and before that in the 1920s.

The most killings were reported in Texas, California, Illinois, Florida and Georgia.

The two law enforcement agencies with the most deaths were the California Highway Patrol and the Chicago Police Department, each with five.

Ten of the shooting deaths came from five cases in which several officers were shot and killed in groups.

The cluster shootings started in February, when authorities say a Fresno County, Calif. deputy was shot by an arson suspect who had vowed to kill investigators and himself rather than go to prison. The killing led to a daylong gunbattle during which a police officer was also shot and killed. The gunman later killed himself.

In March, San Juan authorities say two park rangers serving as guards at Puerto Rico's Department of Natural Resources were gunned down by invaders who jumped a fence during an attempted robbery.

Two West Memphis police officers doing anti-drug work in May were shot to death by two men wielding AK-47s along an Arkansas interstate. The suspects were later killed in a shootout that injured the local sheriff and a deputy at a crowded Walmart parking lot.

In June, authorities say a man wanted for writing a bad check shot and killed two Tampa, Fla., police officers after he was pulled over at 2:15 a.m. And in August, a man was charged with killing two officers chatting in front of his home in the tiny Alaska village of Hoonah.