Maui fire crews continue to monitor a growing brush fire on the western end of Kahoolawe that began Saturday.

As of 9:30 a.m., approximately 6,400 acres of brush have been burned, with the total perimeter of burn area approximately 13 miles long.

Fire officials announced that no active firefighting would take place because of concerns over explosive material in the area. Tradewinds, however, are helping to slow the forward progress of the fire at this time.

The fire that was first reported Saturday spared fuel tanks, solar panels and other key facilities at the Kahoolawe Island Reserve Commission base camp, officials said.

The Maui Fire Department was unable to battle areas of the blaze because of concerns over unexploded ordnance, including rifle bullets and other munition from the 50 years the U.S. Navy used the island for bombing practice.

Since Kahoolawe was returned to Hawaii in 1994, about 65% of the island has been cleared of surface ordnance while 10% has been cleared to a depth of 4 feet (1.2 meters). The uncleared parts of the island are in remote areas where access is limited.

Reserve commission Executive Director Mike Nahoopii said the base camp manager found the fire burned a bathroom and some unusable vehicles but largely spared other facilities.

The commission has about 26 buildings on the south side of the island for volunteers and workers who assist in restoration efforts. The base camp has housing for up to 50 people, a dining hall, kitchen, outdoor meeting facilities, and a research lab.

“I’m really surprised,” Nahoopii said. “It really just stopped feet away from our buildings. I think it’s because the roof runoff saturates the ground, and we’ve been purposely pushing back the vegetation around camp.”

He estimated the cost of replacing the bathroom at $20,000 to $30,000, mostly in transportation expenses.

The Associated Press contributed to this report.