A person is in a critical condition after a grievous assault in broad daylight on a main Christchurch street.

Emergency services were called to the reports of the assault on Fitzgerald Ave around 12.20pm.

A Hato Hone St John spokesperson said they responded with an ambulance and rapid response unit.

One person has been taken to Christchurch Hospital in a critical condition.

Police confirmed they are in attendance, and one person has been taken into custody.

Inquiries into the incident are ongoing.

More to come.