Doug Ward, director of the division of public safety leadership at the Johns Hopkins University School of Education, called the 2010 increase "troubling" but found no obvious explanation.
"Until you look at each one of these cases, it's hard to know the why," he said.
Ward, a 27-year veteran of the Maryland State Police, said it should be no surprise that traffic fatalities exceeded the deaths by firearms. Gun incidents are relatively rare, he said, and some officers never encounter a shooting incident. Meanwhile, virtually every officer is exposed to potential traffic injuries.