Provincial prosecutor Angelito Lumabas, 56, fell on the pavement unconscious after Ernest Keith Nigos, 27, nephew of Mariveles Water District general manager Jimmy Gonzalez, punched him below the right ear.
Lumabas suffered a cut in his eyebrows due to his broken eyeglasses as well as contusions on the face and abdomen.
He complained of chest pain and reportedly vomited blood while he was being rushed to the St. Martin de Porres Hospital.
Nigos was arrested while hiding inside a service vehicle of the Mariveles Water District.
Police said Nigos caught the ire of Lumabas when he shuttled back and forth to the ATM booth carrying six ATM cards to withdraw the salaries of his co-employees at the water firm.
Lumabas was waiting in line at the ATM booth also to withdraw his salary.