Some schools are pulling equipment off the playground as authorities try to determine if a 9-year-old Oklahoma girl died because of something that happened while she played on a teeter-totter-like structure.

Alyssa Avila was playing with several children at a Wyandotte elementary school playground last week on equipment known as the X-Wave, which has plastic hinges and moves up and down. She died after falling off and hitting her head on the turf.

What caused her death is still being investigated, and officials are considering that it may have been natural causes. But several schools around Oklahoma say the episode is enough to make them rethink having the set and other similar equipment in their schoolyards.

Officials in at least six school districts — Moore, Edmond, Oklahoma City, Putnam City, Deer Creek and Norman — have either already removed the structures or prohibited children from playing on them.

At the elementary school in Wyandotte, about 90 miles northeast of Tulsa, the X-Wave has been surrounded by an 8-foot-high chain link fence, School Superintendent Troy Gray said Wednesday.

"No matter what comes of the investigation, it will be removed because of the emotional attachment," Gray said.

The equipment, which cost around $5,000, had been a gift to students from the Parent Teacher Organization and had just been installed in July, Gray said.

Xccent Inc. is the private Minnesota company that makes the colorful X-Wave, the similar X-Wave2 and other playground equipment. Company officials have refused to discuss how their product functions on a playground or how many have been sold to schools across the country until authorities give an official cause of Alyssa's death.

"We would love to share that information with you once the completion of the investigation takes place," said Dan Link, Xccent's vice president of sales and marketing. "We feel it would be irresponsible to make additional comment at this point."

Susan Hudson, education director for the National Program for Playground Safety, said her group had not heard of any other complaints about the X-Wave model. She said the group would not comment further until more information was available because of the questions about how the injury occurred.

The accident happened around 2 p.m. Thursday. Officials say Alyssa hurt her head when she fell backward and hit the playground turf. She was taken by ambulance to a Miami, Okla., hospital where she died about two hours later.

Her parents could not be reached for comment by The Associated Press.

Cherokee Ballard, a spokeswoman for the state Medical Examiner's Office, said two doctors who examined Alyssa found no trauma to her body. Asked whether the oppressive heat might have been a factor, Ballard said she couldn't speculate. It was 97 degrees in Tulsa that day.

Mourners packed the community high school Wednesday morning for Alyssa's funeral, and friends and family members took to Facebook to memorialize her.

(This version CORRECTS temperature in 13th paragraf to 97 degrees instead of 103.)