COSTA MESA – With just over a week until Christmas, South Coast Plaza officials were sent scrambling to find a new Christmas tree after their 96-foot, $120,000 evergreen burned to a cinder early Monday morning.

Flames shot 150 feet skyward, and embers swirled into the dim morning sky, while ash snowed down, witnesses said.

In only five minutes, the tallest Christmas tree in Orange County and one of the largest in the nation was engulfed in a powerful blaze. But fire investigators still don’t know how it started.

“There is no evidence of it being arson, but we haven’t ruled that out,” said Costa Mesa Fire Department spokesman Capt. Chris Coates. “It’s looking like an accidental cause, but the fire investigator isn’t willing to confirm that yet.”

Costa Mesa fire and police officials responded to the fire at 6:37 a.m. and found the tree ablaze outside the Westin South Coast Plaza, 686 Anton Blvd., a hotel just east of the shopping center, which hosts the mall’s Christmas tree and related celebrations. No injuries were reported.

Bradford Williams, 53, a Campbell man staying at the Westin on business, entered the hotel’s lobby to get a coffee, only to be greeted by intense heat from outside and a surreal sight.

“A massive pillar of fire,” Williams said. “People were standing there with their mouths open.”

The flames sent up a large plume of black smoke that could be seen from I-405 Monday morning.

For 34 years, South Coast Plaza has made an annual tradition of buying a towering white fir from the Mount Shasta area of Northern California, transporting the tree 650 miles to Costa Mesa, hoisting it into place with a 200-ton crane, and illuminating it with 20,000 bulbs. This year, the tree arrived Oct. 13 and was lit up Nov. 19.

Debra Gunn Downing, shopping center spokeswoman, said Monday that a new tree would replace the burnt one by the weekend, but said the stand-in would be different than the original.

The 96-foot, 10-ton white fir Christmas tree was brought to the hotel Oct. 13 for a Nov. 19 tree lighting ceremony. It took about a month to decorate.

Fire Capt. Coates said the fire investigators would try to determine whether recent drought conditions played any role in how quickly fire engulfed the tree. The 96-foot evergreen had been doused in fire retardant upon arrival, but Coates said those chemicals do little more than slow minor sparks or embers.

“If the tree is dry and something catches on fire, it’s not going to just put it out, especially in a tree that large,” Coates said.

Coates said Christmas tree fires in homes are common, but he had never heard of a Christmas tree this big burning.

According to the National Fire Protection Association, between 2009 and 2013, U.S. fire departments responded to an average of 210 home fires annually, causing seven deaths, 19 injuries and $17.5 million in property damages per year on average.

Local fire departments telling the public how to keep their homes safe during the holidays by using the hashtag #OCHolidaySafety on social media. Tips include inspecting smoke alarms and furnaces, cleaning chimneys, purchasing fireplace screens and keeping candles and space heaters away from Christmas trees.

Staff Writer Megan Nicolai contributed to this report.

Contact the writer: 714-796-7802 or aduranty@ocregister.com