Authorities are calling a fire that destroyed a playground at a St. Paul recreation center Wednesday "suspicious."

Firefighters arrived at the Baker Recreation Center around 7:23 p.m. and found the slides and climbing structures fully engulfed and wood chips on the ground burned, said St. Paul Fire Marshal Steve Zaccard.

Thick acrid smoke billowed into the air and the fire's intense heat also caused damage to a nearby building owned by the St. Paul Public School District, Zaccard said.

Only metal parts of the equipment were left standing after crews doused the flames. The playground was a total loss and damage was estimated at $25,000. Damage to the building was about $6,000, Zaccard said.

Officially the cause is undetermined, Zaccard said, noting that investigators could not rule out that something such as an improperly discarded cigarette could be the cause. But that is unlikely being that several adults and children were present at the time, he said.

"It would be surprising that the fire would grow that big at 7:23 p.m. with people around," he said. "That's why we think it's suspicious."

St. Paul Police spokesman Mike Ernster said a recreation center employee spotted the fire and called 911.

Nobody was hurt and police have not made any arrests as of Thursday morning, Ernster said.

"This deprives children of a place to play," Zaccard said. "It's a loss for the neighborhood and the school."

On Thursday, the city filed a claim with its insurance company and said it plans to rebuild the playground, said Clare Cloyd, a spokeswoman with the parks department.