Firefighters from the Bunbury and Harvey shires were among the hundreds who banded together to fight a major bushfire in the Margaret River region over the past week. More than 7800ha of bushland in the Leeuwin-Naturaliste National Park was lost in the blaze, which began on Wednesday, December 8, and is believed to have been deliberately lit. The Bunbury Volunteer Bush Fire Brigade, Eaton-Australind Volunteer Fire and Rescue Service, and Leschenault Volunteer Bush Fire Brigade headed to the blaze on Thursday to help control the fire as part of the South West Taskforce. The Leschenault Volunteer Bush Fire Brigade ran asset protection and stopped a blaze from crossing a road into dense vegetation during the first days of fighting. Officer-in-charge Wayne Jackson said crews from the region would help out and expected nothing in return during events such as this one. “It happens all the time, and we do it without favour,” he said. “It was good to see people from all over coming together for the fire when necessary. “Especially volunteers. It is a big ask, and it is amazing what guys will do to get in there and help out.” The bushfire forced residents to evacuate on Thursday before being downgraded to a watch and act on Sunday. “Bussell Highway is now open and we are looking to open up the Boranup community for those that haven’t been able to return yet,” a Department of Fire and Emergency Services spokesperson said on Sunday. “The weather has been very kind to us.” Police revealed on Saturday they believed someone deliberately lit the fire near Mammoth Cave, based on an initial assessment of the scene. “Detectives would like to hear from anyone who saw any suspicious activity in the vicinity of Mammoth Cave on Wednesday (December 8) or who has dash-cam or mobile phone vision of people or vehicles in the area at the time,” police said in a statement on Saturday. DFES incident controller Brad Barton said there were no reports of homes lost, and the blaze had been mainly contained to the national park. Mr Barton said on Sunday residents should still take the situation seriously and monitor the Emergency WA site for updates. “Fire is unpredictable and ... things can go awry at times,” he warned.