All three sides play in Prima Categoria, the eighth tier of the league.
Bagheria, needing a point to qualify, were 4-3 behind with 10 minutes to play in Wednesday's game when Borgata hit two goals in quick succession.
Borgata players then watched in bewilderment as their opponents scored one own goal after the other, shared between three players, Italian media said.
The result meant Terrenove qualified on goal difference ahead of Partinicaudace.
"It had been a real contest up to a certain point then Bagheria staged a farce," Borgata coach Ignazio Chianetta told the website Siciliaingol.
"Their captain told me they preferred us to qualify rather than Partinicaudace.
Partinicaudace coach Giovanni Cammarata said: "I can guarantee there was no agreement between us and Bagheria.
"I can't try to understand a motive for these eight own goals. It has nothing to do with football and I hope the FIGC investigates."
Sandro Morgana, the FIGC's regional president, said: "I will personally inform our prosecutors about this and they will look into the case and establish which sanctions should apply."
(Reporting by Brian Homewood; editing by Tony Jimenez)
