Homicides, gang-motivated shootings, rape and robbery rose in New York last year, slowing to 1.7 percent an overall decline in major crime, officials announced Monday.

Major crime rose three percent in Manhattan and four percent in the Bronx, two of the five boroughs that make up America's largest city, deputy police commissioner Dermot Shea told a news conference.

Crime rates are closely watched in New York, the financial and entertainment capital of the United States, and have fallen steadily since "zero tolerance" policing was introduced in the 1990s.

But the city saw 348 recorded homicides in 2015 -- a number likely to rise further due to another recently reported incident -- an increase of 4.5 percent on 2014's record low.

More than two-thirds of homicides -- 68 percent -- were the result of gunfire, itself a jump of 21 percent from 2014, Shea said.

The vast majority of victims were men from ethnic minorities. African Americans accounted for 64 percent of homicide victims, Hispanics 27 percent, whites six percent and Asians three percent, the police said.

Nearly all victims -- 76 percent -- also had a history of arrest, drawing a picture of violent crime concentrated among known criminals, often out late at night and involved in criminal activity, police said.

Despite the jump in homicides, police stressed Monday that New York still has a lower murder rate than Chicago, Houston, Los Angeles and Philadelphia.

The overall decline of 1.7 percent in major crime in 2015 follows a much steeper decline of 4.6 percent from 2013 to 2014.

Crime rates have fallen steadily for decades in New York, where the number of homicides peaked in 1990 at 2,248 -- six a day on average -- before the advent of then mayor Rudy Giuliani's policy of "zero tolerance" policing.

While shootings fell three percent in 2015 overall, gang-motivated shootings rose 18 percent, police said. Nearly 50 percent of all shooting incidents involved someone in a gang, Shea said.

Manhattan saw 29 more shootings than in 2014 and statistics show that victims and killers tend to be known to police with an arrest history.

Recorded rapes increased six percent and robberies rose two percent from a 20-year low in 2014, despite a 10-percent decline in burglaries, Shea said.

Crimes on the transit system rose by 10 percent in 2015, driven by grand larceny and robberies.