A storage tank compound in Lyttelton. Photo: CityCare
A Fire and Emergency NZ spokesperson said crews were called to the scene about 9.40am after reports two people were trapped in a tank.
Police said the pair were found unconscious in a tank aboard a ship.
Two fire crews from Lyttelton and one from Christchurch were able to get them out of the tank.
A Lyttelton Port Company spokesperson said there was "an incident on board a vessel in the dry dock".
No port staff were involved in the incident, the spokesperson said.
Hone Hato St John told The Press there was a "chemical incident" and several people were taken to Christchurch Hospital in a serious condition.
