A small moorland fire on Darwen Moor at Belmont was reported to Lancashire Fire and Rescue Service.
When crews arrived, the fire turned out to be much bigger than first reported.
A five acre fire was covering Darwen Moor.
Firefighters from Lancashire and Manchester were brought in to help extinguish the fire.
Lancashire Fire and Rescue Service said that by the time it went dark the fire was still spreading and firefighters went into ‘defensive mode’ to ensure that the five farms in the area were protected.
At 5am this morning, 12 fire engines from Lancashire and Manchester were sent to the fire so firefighters could begin to attack it as soon as day had broken.
All walkers are reminded to take extra care on the fells and moors at this time of the year.
Further information will be released by the service throughout the day.