A Boston Police officer shot and killed a 19 year-old man who was allegedly firing a gun at officers during a pursuit in the area of Town Field and Melville Avenue on Monday afternoon.

The incident took place around 5:15 p.m., according to BPD Commissioner William Gross, who briefed reporters at police headquarters on Monday night, several hours later.

Gross said that police on bicycle patrol responded to Town Field for a report of gunshots and began pursuing two men. One of the suspects ran to Penhallow Street and the officers followed him - with one officer getting off his bike to chase him on foot, Gross said.

The man pulled out a gun, Gross said. The two officers yelled at him several times to drop his gun. Instead, Gross said, the man opened fire.

Gross said neither of the officers was hit. After the suspect fell to the ground, he said, the officers ran to him and began performing first aid until Boston EMS paramedics arrive.

His alleged accomplice remains at large, Gross said.

The commissioner said the officers were not wearing body cameras, but that C-11 officers, who quickly responded to the scene to assist, were. Footage from their cameras will be reviewed as part of an investigation by both Boston Police and the Suffolk County District Attorney's office into the incident, he said.

In a statement issued on Tuesday evening, DA Rollins said: “The sequence of events last evening that began with a shooting in a crowded park in the Fields Corner section of Dorchester and ended with a loss of life on Penhallow Street has left the city shaken.

“I am thankful for the immediate response of the Boston Police Department and that none of those officers were injured," Rollins added. "I would be remiss if I did not thank the many witnesses from the community who came forward to aid investigators at the scene. If there is anyone in the community with additional information, please bring that to my office directly.

“I also acknowledge that a family has lost its loved one; to them, I express my sympathy. As your District Attorney, it is my office that holds exclusive jurisdiction over any death investigation, including police-involved shootings. I assure that family, members of law enforcement, and this community that there will be a complete, impartial, and transparent review by my Discharge Integrity Team, and we will make our findings available to the public. As we lead our independent investigation into the events that unfolded yesterday, we ask for patience and calm; violence or the threat thereof have no place in our community.“