A call for a robbery in Williamsbrigde ended with a sergeant hurt and an 18-year-old suspect shot, police say.

The NYPD say the incident began around 9:15 p.m. Thursday when a father called 911, saying his own son had robbed his mother and brother at gunpoint inside their home on Van Nest Avenue.

Investigators say officers and the father tracked the suspect to an apartment building on East Gun Hill Road.

Before Emergency Service officers arrived, police say they heard three gunshots from inside the apartment. The suspect ran out the front door and struggled with officers as they tried to take him into custody.

Police say during that struggle, one sergeant fell and hit his head, and another officer fired his weapon, hitting the suspect in the lower back and arm.

A loaded gun was recovered inside a bag the suspect was carrying, according to police. Both the officer and the suspect were taken to NYC Health + Hospitals/Jacobi.

The suspect is in critical condition, and the sergeant is expected to recover.

The investigation is ongoing.