Police are seeking sightings of a grey Mitsubishi Diamante believed to have been involved in a hit and run in Taitā, Lower Hutt, on Saturday afternoon.
Police first received a report of the car vs pedestrian crash on High St at around 12.10pm.
A woman, described by a witness as a young woman, was taken to Wellington Hospital with serious injuries.
The witness told the Herald she arrived about 20 seconds after the hit-and-run and a trainee nurse helped the injured victim.
She also said members of the community helped look after the woman and diverted traffic before emergency services arrived.
Police said immediate work was undertaken to locate the vehicle involved, including reviewing closed-circuit television cameras in the area.
Further CCTV is still to be obtained over the following days.
Police believe the vehicle may be missing a left front fog light surround and have a broken windscreen.
"Inquiries into this incident are ongoing and we encourage the driver to report to their nearest police station," a police statement said.
"Any members of the public that recognise the vehicle or have any information regarding the crash are urged to contact us on 105, quoting file number P045322349."