According to The National, they were all released on bail of just 300 kina ($A137) each.
Only two were from a Mount Hagen-based mobile squad unit.
National Capital District criminal investigation division chief director Mark Yangen reportedly said more arrests were on the way.
The incident caused more divisions in the country's police force - especially as the victims revealed to PNG's press it was politically motivated.
Up to 70 "rogue" police officers overwhelmed the highway patrol team, according to one witness who also received blows.