UPDATED 9.09PM: It's an early start to the fire season in South Australia today after a grass fire quickly took hold north of Port Wakefield this afternoon.

It started in crops, and burnt through more than 16-hundred hectares of stubble, before CFS crews halted the spread of the blaze.

Crews will remain at the scene throughout the night, to fully extinguish the flames.

CFS state co-ordinator Brenton Eden says people have been injured in the blaze.

He says one man, who could have been one of the first responders to the fire, was admitted to hospital with serious burns