St. Paul Mayor Chris Coleman along with others looking into a deadly landslide at Lilydale Regional Park last spring released the findings of two independent investigations Thursday.
The Star Tribune reports the failure of the saturated slope that buried four children, killing two of them, on May 22 could not have been predicted.
Ryan Benson, senior engineer at Northern Technologies Inc., said there are a number of environmental factors that prompted the landslide, but the cause doesn't come down to a single item.
Benson determined heavy rainfall in the area played a role and ruled out any "man-made" activities, such as construction, as a contributing factor.
Northern Technologies' said due to the natural erosion process, there will be more landslides in the future, but when and how severe aren't possible to predict, KARE 11 reports.
A second investigation headed by Don Lewis, Dean of Hamline Law School, gathered information from St. Paul employees, studied emails and city files. The Associated Press says that while city officials knew soil erosion was an issue in the park, there's no evidence that they knew unstable bluffs posed a risk.
Nine-year-old Haysem Sani and 10-year-old Mohamed Fofana were killed and two other fourth-graders, Lucas Lee and Devon Meldaha, were injured when the ground collapsed, sending them into a pit with rising water.
The four were among about 50 students from Peter Hobart Elementary in St. Louis Park on a field trip at the park to hunt for fossils.
The mayor says the park will likely remain closed for the rest of the year until a protocol can be put in place to make the public more aware of the risks.