Warring gangs have driven New York’s murder rate to an 8 percent spike through the first half of the year, authorities said Tuesday.

The city saw 147 murders through the end of June, an increase of 11 from the 136 notched to the same point in 2017.

“We were all quite sober about the fact that trying to repeat what happened in 2017 was going to be very, very difficult,” said Mayor Bill de Blasio at the briefing, invoking last year’s record-low crime numbers. “There’s also real work we have to do and some real specific things we have to address.”

Among those issues is gang violence that has accounted for roughly one-third of this year’s slayings — and spilled over to the mainstream last month with the mistaken-identity slaying of innocent Lesandro “Junior” Guzman-Feliz by a band of blade-wielding Trinitarios.

“When it comes to the homicides, it’s around 30 percent [gang-related],” said NYPD Chief of Department Terence Monahan. “When we come to non-fatal shootings, it’s around 40 percent where there’s some sort of gang nexus. And those are the ones we know about.”

Much of that bloodshed has come in the Bronx, which has seen 51 homicides so far this year, up 64.5 percent from last year’s 31 to the same date, department stats show.

“The Bronx is driving the murder year-to-date,” Monahan noted.

To combat those trends, the NYPD is deploying additional officers to two of the borough’s most crime-ridden precincts: the 40th, which hosted Tuesday’s meeting, and the 48th, where gangs and homicide intersected in horrifying fashion last month with the slaying of Guzman-Feliz, a 15-year-old aspiring cop.

Guzman-Feliz was yanked out of a bodega and hacked to death with machetes and knives by a mob of Trinitarios gangbangers who confused him with a rival.

Twelve suspects have been arrested so far in the gruesome murder.

Despite the troubling homicide spike, overall crime reports are down 1.8 percent on the year, including drops in robberies, felony assaults, and shootings, officials said.

Rape reports have spiked by 33.2 percent in 2018 — from 678 last year to 903 this year — but Monahan attributed much of the hike to sexual assault in the news, as well as increased reporting of domestic attacks and previously unreported incidents from years past.