A neighborhood dispute turned deadly in Costa Rica after a man opened fire on another guy ... and the horrific moment was caught on video, which shows the killing.

In the harrowing surveillance footage from earlier this week that's making the rounds, 2 neighbors and their respective wives are seen getting into an argument, yelling at one another from their adjoining homes in the city of Escazú. The disagreement moves to the front yard, where the 2 parties continue to hurl words back and forth.

As the argument heats up, Otoniel Orozco Mendoza -- the man who ended up getting shot, and later identified by local media -- makes the quarrel a physical one ... throwing punches at his neighbor, Eduardo Ramírez Zamora. Unfortunately, Zamora pulled a gun out in response.

Zamora ended up firing at least 9 shots at Mendoza ... at point-blank range, mind you.

Mendoza's wife is seen screaming and fleeing as the shots are fired, with Zamora's wife pulling him back ... attempting to stop the disturbing scene. They both eventually run off.

The incident, which took place Monday, was fatal for Mendoza -- who was pronounced dead at the scene after first responders arrived. According to La Nacion, the couples had been arguing about their shared water valve.

Zamora was arrested by authorities after the incident.

Mendoza, who was originally from Nicaragua, was a businessman who worked in private security. In addition to his wife, he is survived by his daughter and son. He was 53.

RIP