PARK CITY, Kan. — A Kansas fire marshal said Tuesday he's hopeful that fire crews supported by water-dropping helicopters can control a wood pallet fire at a Kansas recycling center that has been raging for days.

There have been no reports of injuries or damage to other buildings from the fire, which started Sunday night at Evergreen Recycle in suburban Wichita. Firefighters have been working to control its spread to a nearby business.

The cause of the fire is under investigation.

Strong, straight-line winds and temperatures in the 90s have complicated firefighters' work.

''We're hoping we're going to be able to get it under control today,'' Sedgwick County Fire Marshal Brad Crisp said Tuesday. ''We're really worried about the wind conditions, not only today but tomorrow.''

Air National Guard helicopters on Tuesday began dropping up to 600 gallons (2,271 litres) of water on the blaze every 10 minutes, Crisp said. The guard stepped in after Sedgwick County officials on Monday declared a local disaster.