The teenaged girl then entered a walkway that runs between Mander Place and Otaki Street and was seriously assaulted by the first man wearing black.
Police said the second man was considered to be a witness in this matter and may provide information about the girl and the other man dressed in black clothing.
Other passengers on the bus may also recall seeing the man wearing black, and Police encouraged anyone with information to contact Detective Tim McIntosh at Wellington Central Police Station on 04 381 2000.
Alternatively, information could be provided anonymously through the organisation Crime Stoppers on 0800 555 111.