Washington ? Murders were up slightly nationwide during the first six months of the year, with gang violence contributing to more killings in some of the nation’s largest cities, the FBI reported Monday.

The number of murders rose 1.1 percent nationwide while overall violent crime declined 3.1 percent. New York, Baltimore and Philadelphia were among the cities with an increase in homicides.

The reasons for the increase vary by city, but experts said there clearly has been a resurgence in gang activity in some places.

The preliminary draft of the FBI’s Uniform Crime Report, based on reports from 9,908 state and local law enforcement agencies, does not include raw totals for categories of crimes, only percentages.

The six-month totals for 2003 marked the third consecutive time the FBI has recorded a decrease in overall violent crimes but an increase in murders.

Overall, there were 4.3 percent more murders in the Northeast during the first half of 2003 compared with last year. There also were slightly more homicides in the South and West, with only the Midwest showing a decrease (-1.9 percent).

Even with the national increase in murder, overall violent crime fell. Other violent crimes measured are forcible rape, robbery and aggravated assault.

The number of arsons — measured separately — dropped 10 percent from year to year, with every part of the country seeing fewer criminal fires set in the first half of 2003.