Police arrive at the scene of a shooting at a Home Depot store in Manhattan's Chelsea neighborhood of New York, January 25, 2015. REUTERS/Carlo Allegri

By Barbara Goldberg

NEW YORK (Reuters) - New York City, once notorious for high crime, broke a record on Thursday with no murders reported for 10 straight days, police said.

The historic calm achieved at 12:01 a.m. Thursday comes on the heels of a notable year - murders in New York City in 2014 fell to an all-time low of 328, the fewest since the New York Police Department started keeping reliable records in 1963.

"Everybody is behaving," said Sergeant Daniel Doody of the New York City Police Department.

The biggest U.S. city kept the peace through the early morning on Thursday, beating the milestone set in 2013, when nine days in a row passed without a single person killing another.

This year's notable zero comes in the wake of Mayor Bill de Blasio's struggle to mend a serious rift between City Hall and the country's biggest police force. Officers in late December embarked on what city leaders called a slowdown, expressing anger over the mayor's qualified support for some of the NYPD's fiercest critics. As a result, the number of arrests and court summonses plummeted at the time.

With cold weather forecast for coming days, it's possible that cooler heads may prevail even longer, said Doody, who noted killings often take place in the warmer seasons when more people are out on the street and the hot weather makes them "cranky."

"But if I could predict that, I would have won the Powerball last night," Doody said.

Police had attributed their year-long success in 2014, in part, to a greater focus on the small number of people responsible for most offenses. Murders were down 85 percent from their peak in 1990.

It is part of a decades-long fall in overall U.S. crime, with other big cities reporting a drop in violent crime in 2014, including Chicago with its lowest number of murders since 1965.

(Reporting by Barbara Goldberg; Editing by Scott Malone and Lisa Lambert)