An off-duty Pennsylvania police officer died Wednesday, three days after being shot three times in the back during an argument, according to reports.

“This is a very, very hard day for the Pittsburgh Bureau of Police,” police Chief Scott Schubert said. “Our hearts go out to the family of Calvin Hall, it goes out to our officers, it goes out to our community because we're all suffering from what happened,” the Pittsburgh Post-Gazette reported.

Officer Calvin Hall, 36, had been visiting a Pittsburgh neighborhood where his cousin lives. He later returned because a man had threatened his cousin and wife with a gun near their home.

OFF-DUTY POLICE OFFICER IN CRITICAL CONDITION AFTER BEING SHOT MULTIPLE TIMES: REPORTS

“It just weighs heavy on me because he came back to make sure I was all right,” Hall’s cousin, Darnell Coates, told the paper.

Hall reportedly became embroiled in an argument between several people in the middle of the street and as Hall turned to walk away he was shot three times in the back, according to the Post-Gazette.

Coates said he thought the shots were indiscriminate. “Any of us could have got hit,” he said.

He said he thinks he knows the identity of the shooter and hopes to help police find him.

Pittsburgh Mayor Bill Peduto gave his condolences in a statement Wednesday.

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“On behalf of all residents of the City of Pittsburgh I want to express my deepest condolences to the family, friends and coworkers of Officer Hall, a man who was deeply committed to his public service to the community.”

Police detained several people present at a house party across the street from Coates’ house for questioning, but no arrests have been made, according to the Post-Gazette.

Hall was a two-year veteran of the department.

Fox News' David Aaro contributed to this report.