The 80-year-old man who killed a man when he opened fire at a senior-living facility Thursday was enraged at the victim because of a feud over a caretaker, a report said Friday.

Robert Breck burst into the lobby of the high-rise building in Vancuover, Washington, and started arguing with 75-year-old Dean Tunstall over 44-year-old caretaker Shawna Garris, CNN reported.

Breck allegedly yelled at Tunstall, shouting that he was lying about knowing Garris, according to the report.

He then allegedly pulled a gun and began shooting, killing Tunstall and wounding Garris and one other woman, auhtorities said.

Garris told police she had been Breck’s caretaker for a year, but was fired when she rejected his offer to be his mistress, according to CNN.

Police arrested Breck after an hours-long standoff. He told officers that he opened fire because he had an ongoing feud with Tunstall and “couldn’t take it anymore,” according to the report.