COVINGTON, Wash. -- A fire continues to burn a pile of scrap wood at a wood recycling business in Covington, 12 hours after it started, reported KIRO 7 Eyewitness News.

SLIDESHOW: Wood Debris Goes Up In Flames

The two-alarm fire at Rainier Wood Recyclers started around 10:30 p.m. Tuesday and involves a wood pile that is about 30 feet high. The Kent Fire Department said the heat from the fire is so intense that the water evaporates before it reaches the wood. The only option is to let the fire burn out and to contain the blaze to prevent it from spreading, they said.

Firefighters said the fire has already burned 2,000 tons of clean wood and is expected to burn well into Wednesday afternoon. A company spokesman told KIRO 7 that the wood is pallets and crates that do not contain any painted or treated material.

The fire is sending a large plume of smoke into the already stagnant air, and a current smog watch is expected to be in effect until Wednesday night.

The flames lit up the night sky Tuesday, prompting numerous residents from miles away to call both KIRO and 911. Others, who could see the fire from Highway 18, stopped their cars on the side of the road to watch or take pictures.

Investigators said that initially the wood pile was about 175 feet long and 50 feet high. Crews using heavy equipment were brought in remove some of the wood from the mound while others continued to spray water around the perimeter to keep the flames from spreading.

As soon as the fire burns out and the wood pile cools, investigators will look into what may have started the blaze.

The company spokesman said he’s not sure how much in total he'll lose from this fire.