Six people, including a New Jersey police officer, were killed in an hourslong standoff in a Jersey City, NJ, neighborhood Tuesday, investigators said.

According to ABC News, a spokesman for the Hudson County (NJ) Sheriff's Office said its officers and Jersey City Police Department officers responded to reports of shots fired at a cemetery.

The shootings unfolded in the cemetery and at a convenience store near the Sacred Heart School, reports Fox News.

Of the six people who died, one was a married 39-year-old police officer with five kids. The others killed included two of the three suspects in the case, as well as three civilians.

A second officer was struck in the shoulder by gunfire, and two others were hit by shrapnel, Mayor Steven Fulop said.

It was unclear what happened to the third suspect.

The circumstances of the shootout also remained uncertain and the situation forced every public school in Jersey City into lockdown mode.

The FBI was assisting Jersey City police.