St. Paul Mayor Chris Coleman's office said two investigations concluded the city lacked enough information about erosion in the area of Lilydale Regional Park "to predict or prevent" the landslide in May, the Minneapolis Star Tribune reported.
The investigation led by Northern Technologies Inc. Senior Engineer Ryan Benson pointed to "additional groundwater accumulation" from recent rains, saying it doubted any "man-made" activities contributed to the landslide.
"Changes occurring within the natural environment, combined with ongoing weathering impacts" were likely factors, the Northern Technologies Inc. report said.
Fourth-graders Mohamed Fofana, 10, and Haysem Sani, 9, from Peter Hobart Elementary School in St. Louis Park, died after a cliff collapsed May 22. Two other children were injured. The students were searching for fossils when the hillside fell.
Also released Thursday were findings of an investigation led by Hamline University Law School Dean Don Lewis. Lewis' team reviewed in-depth the city's internal workings in the landslide as well as visited the site several times, the Star-Tribune said.
"My heart goes out to the parents and families of Mohamed and Haysem and others hurt or impacted by the May 22 landslide," Coleman said in a statement. "Moving forward, the city will work closely with the National Park Service and other partners to assess and review our Lilydale Park operations plan."