A police officer was shot while on duty in the Bronx Saturday evening by a person who is still at large, the NYPD said.

Police say it happened just after 8:30 p.m. 

According to the NYPD, a man came out of a building on Simpson Street between Fox Street and Southern Boulevard and engaged two officers in a marked police van in conversation.

He then allegedly fired shots into the van, hitting one of the officers in the chin and neck, according to police. 

The officer who was shot is expected to survive, according to officials. The other officer was not hit.

"I want New Yorkers to be clear. This was an attempt to assassinate police officers," said Mayor Bill de Blasio. "Out in the open, an individual walked up to a police van with the intention of killing police officers. This is absolutely unacceptable in this city or any place."

"Without provocation, the man pulls out a gun. The operator of the van yells 'Gun!' and immediately attempts to put the car into drive and pull away from the scene," said Police Commissioner Dermot Shea. "At this point in time, what we know is that multiple shots were fired by the perpetrator at close proximity into the van."

Shea says the officers did not return fire.

The suspect is described as a man in his 30s who was wearing a black jacket.