More than 100 firefighters from across Hampshire have been tackling a fire at a distribution warehouse in Andover.
The alarm was raised on Tuesday morning.
There are no reports of any injuries.
By Tuesday afternoon more than 20 fire engines and support vehicles had been deployed to the scene.
The automated warehouse does have a human presence, but it is staffed by robots that can pack 65,000 grocery orders a week.
A spokesperson from Ocado said that the fire started in a machinery section.
They said that all ''relevant safety measures" had been carried out as planned, and added: "The incident and the measures being taken to contain it appears to have affected a proportion of the mechanical handling equipment and some of the grid."
The online retailer has had to suspend customer orders from the warehouse.
The firm said it will update customers as soon as it can.