New York has marked its first weekend without a shooting in 25 years, police said Monday.

"We went Friday, Saturday, Sunday without any shootings and homicides," New York Police Department chief James O'Neill told reporters.

"That's the first time in decades, and that's something not just the NYPD, but all New Yorkers can be proud of."

The last time the most populous US city of 8.5 millions had a weekend without shootings was in 1993, according to police.

But there have been intermittent spikes. The weekend of October 6-7, for example, was "terrible", with several shootings in Brooklyn and the Bronx, authorities said.

The number of murders is on the rise again this year, after hitting a low in 2017 with 292 total -- a record since the 1950s.

In the first half of 2018, the city recorded 147 murders, an eight per cent increase over the same period in 2017, and mostly in Brooklyn and the Bronx.