WASHINGTON — The number of violent crimes committed across the country was up in the first half of 2015, compared with the same period a year earlier, with increases spanning different types of crimes, federal authorities said Tuesday.

The numbers of murders, rapes, assaults and robberies were all up over the first six months of 2015. Overall violent crime was up 1.7 percent, an increase that followed two consecutive years of declines, according to the FBI.

These figures come after a year that saw murder rates go up in cities nationwide. The numbers are among the preliminary data released by the FBI as part of its Uniform Crime Reporting program, which relies on the voluntary participation of more than 18,000 law enforcement agencies.

Nationwide, murders were up 6.2 percent, with the biggest jumps in the smallest and largest areas. Murders rose 17 percent in areas with fewer than 10,000 residents, 12.4 percent in places with between a half-million and 1 million residents and 10.8 percent in places with more than 1 million people.

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The FBI found that violent crime increased in most regions, with one notable exception. It actually fell by 3.2 percent in the Northeast, even as it ticked up by 5.6 percent in the West, 1.6 percent in the South and 1.4 percent in the Midwest.

An FBI investigator investigates the scene of a shooting outside a military recruiting center in Chattanooga, Tenn. from July 17, 2015. Violent crime rose across in the country in the first six months of 2015 compared to the same period the year before, according to preliminary data released Tuesday,Jan. 19, 2016, by the FBI. Photo Credit: AP / John Bazemore

The overall violent crime rate has fallen significantly over two decades, from 79.8 victimizations per 1,000 people in 1993 to 20.1 per 1,000 in 2014, Justice Department figures show.