Days before the 2018 hurricane season begins on June 1, a new report sheds light on a devastating 2017 storm.

According to a new study from Harvard University researchers, at least 4,645 people died in Puerto Rico as a result of Hurricane Maria, which hit the island on September 20. The official government tally is 64 fatalities.

“Our results indicate that the official death count of 64 is a substantial underestimate of the true burden of mortality after Hurricane Maria,” the authors—researchers and scientists at Harvard T.H. Chan School of Public Health and Beth Israel Deaconess Medical Center—wrote.

Per The Washington Post:

The Harvard findings indicate that health care disruption for the elderly and the loss of basic utility services for the chronically ill had significant impacts, and the study criticized Puerto Rico’s methods for counting the dead—and its lack of transparency in sharing information—as detrimental to planning for future natural disasters. The authors called for patients, communities and doctors to develop contingency plans for such disasters.

Puerto Rico Governor Ricardo Rosselló spoke at a news conference on Tuesday (May 29), saying, “We want the real numbers to come out. We had a protocol that really was sub-par and we recognize it and now towards the future we want to make sure that it is effective.” In response to previous criticism that the official death count was too low, Rosselló requested that researchers from George Washington University review the government’s death certification process. The results are expected in June.  

Since the Harvard study’s release on Tuesday (May 29) in the New England Journal of Medicine, there has been widespread condemnation of the government’s assertion that so few died in the storm. Politicians, activists and organizations that provide aid took to Twitter to react to the report: