HOBOKEN -- Two police officers were injured and four people were arrested during an early morning fight outside of a Washington Street bar on Saturday, police said.

As many as 40 people were involved in the 4 a.m. incident near Hoboken Bar and Grill, Hoboken Police Chief Ken Ferrante said.

While the officers did not suffer serious injuries, a sergeant is out of work while recovering.

Ferrante went on Twitter to issue a warning to the city's nightlife establishments, which draw large weekend crowds.

"Bars or restaurants that can't control crowds will not be tolerated," the city's top cop said Saturday.

Officers patrolling Washington Street noticed a large fight involving men and women. While police were trying to break up the crowd, "small pockets" of fights began to form, authorities said.

At one point, 23-year-old Christian Caputo, of Jersey City, threw Police Officer Michael Losurdo to the ground. Losurdo was able to arrest Caputo, despite suffering a leg, ear, and head injury, police said.

Two other men -- later identified as Robert Rosario, 21, of Jersey City, and Frank Henderson, 22, of Hoboken -- tried pulling on Caputo to help him avoid being arrested. Rosario and Henderson fled the area after police regained control of Caputo, authorities said.

Officers led Caputo to a police car and a crowd began to form around them. Sgt. Michael Costello tried creating a pathway when 21-year-old Hashim Dyer, of Hoboken, jumped on top of the cop from behind, police said. Costello suffered a back injury.

Rosario and Henderson were both brought into custody a short time later, authorities said. All four were charged with aggravated assault.

NJ Transit, State Police, North Bergen, and Port Authority all assisted Hoboken "during the moment of chaos."