Here’s what’s been happening in New York City over the...

New York City has been rocked by at least four attacks over a 30-hour period that are now being investigated as anti-Semitic hate crimes — including one against two little boys in Williamsburg, cops said.

The crime spree began Monday in the lobby of a NYCHA building where the boys, ages 6 and 7, lived on Wilson Street, officials said.

The pair was attacked from behind at around 8:40 p.m. by two teenagers — one of whom struck the younger victim in the stomach. The boys suffered minor injures and were treated at the scene.

The perps said nothing in the alleged attack — but police are investigating the incident as a hate crime because “it’s usually better safe than sorry,” an NYPD spokesman said.

Also on Monday, a 65-year-old Jewish man in a yarmulke was punched and kicked by a hate-spewing man on East 41st Street near Third Avenue in Manhattan.

“F–k you, Jew bastard,” Steven Jorge, 28, of Miami allegedly spat. He has been charged with assault as a hate crime.

Two other anti-Semitic attacks were reported Tuesday in Crown Heights.

The first occurred at around 1:40 a.m. on Kingston Avenue, where a group began hurling anti-Semitic slurs at a 25-year-old man who also had a drink chucked at him. He did not suffer any injuries.

Just after 5 p.m. that day, a 56-year-old man was punched from behind by a group of people while walking on Union Street. He refused medical attention.

The four incidents, which are being investigated by the NYPD’s Hate Crime Task Force, left elected officials outraged.

“Horrified to hear that during this holiday season, 2 Hasidic Jewish boys, ages 6 and 7, were punched in their own building at 99 Wilson St,” tweeted Democratic city Councilman Stephen Levine, whose district includes Williamsburg and other parts of Brooklyn. “This is a @NYCHA development in which the Hasidic community has lives side by side in harmony with the broader community for decades.”

Mayor Bill de Blasio, meanwhile, called for the perpetrators to swiftly be brought to justice.

“It’s not enough to condemn anti-Semitism — we have to confront it,” Hizzoner tweeted Wednesday.

The Anti-Defamation League is offering a $10,000 reward to anyone with information on the Crown Heights attack.

Year-to-date, New York City has seen a spike in hate crimes, with a 20 percent surge in anti-Semitic attacks, according to NYPD statistics as of Sunday.

Additional reporting by Ben Cohn