Nearly 3,000 Puerto Ricans died as a result of the devastation caused by Hurricane Maria last year, a number that dwarfs the government’s initial tally of 64, according to a report commissioned by Puerto Rican officials and released Tuesday.

Gov. Ricardo Rosselló, who asked for the research following criticism of the American territory’s low death count, said his government accepts the new numbers and wants to learn from the crisis.

“The magnitude of the catastrophe was without precedent in Puerto Rico and there was certainly disagreement with the total number,” Rosselló said at a press conference. The report was completed by researchers at the George Washington University’s Milken Institute School of Public Health who examined death records for six months after the storm and attributed 2,975 deaths to the disaster.

In comparison, Hurricane Katrina, which is one of the deadliest storms in U.S. history, killed more than 1,800 people.

Hurricane Maria barreled into Puerto Rico Sept. 20 as a Category 4 storm. Destruction was widespread, severely crippling the island. Both the electrical and water systems were knocked out in some areas for months. Hospitals and other public health services were damaged, doctors’ offices lost power and often remained closed and medical supplies were difficult to find.

Health advocates scoffed at the government’s initial death toll and said many people died after the storm because they lacked medicine, couldn’t get adequate medical treatment or had chronic diseases that were aggravated by the post-storm conditions.

The official government estimate of 64 deaths was low because it counted only those directly attributable to the storm, such as drowning deaths or injuries caused when buildings collapsed, according to the report. The George Washington researchers instead inspected death certificates and other records, and they calculated the excess deaths by comparing historical death rates to the actual number of people who perished.

In addition, the GW researchers analyzed death statistics for age groups, gender and geography.

“I would say this is a study that can provide everybody a sense of security that, yes, this is a number that you can use as a reference for the future,” said Carlos Santos-Burgoa, principal investigator and professor of global health at GW’s  school of public health.

According to the study, the number of excess deaths is 22 percent higher than what would be expected had the hurricane not hit the island. The risk of dying for men over the age of 65 was 35 percent higher than the baseline, and it remained elevated through the end of the study. And people living in poorer areas were 45 percent more likely to die.

Santos-Burgoa said the risk people in poorer municipalities faced is a “major concern” because it shows the level of inequity on the island before the hurricane hit and was exacerbated in the aftermath.

“It’s a very strong message in Puerto Rico and people addressing natural disasters all over the world: Don’t treat people as homogenous groups,” Santos-Burgoa said.

At a briefing for reporters in San Juan, Rosselló discussed several initiatives to bolster the island’s disaster preparedness, including counting vulnerable populations like the chronically ill and creating a commission to handle recommendations to improve the island’s emergency response systems.

“This is a time for Puerto Ricans to bind together, to mourn, to reflect on the things that were done properly and things that were mistakes,” he said. “And have the firm commitment to identify those mistakes and make sure that moving forward toward the future, those mistakes aren’t committed.”

The report is the latest in a series of analyses done by universities and one newspaper to answer the question of how many perished in the storm.

A survey published in May in the New England Journal of Medicine estimated more than 4,600 excess deaths occurred from the day the hurricane made landfall to the end of the year. A separate investigation by The New York Times found 1,052 lives lost. A research letter published in JAMA in August estimated more than 1,100 deaths.

Earlier this summer, Puerto Rican officials quietly released data that dramatically upgraded its official death toll to 1,427.

The researchers also examined Puerto Rico’s crisis communications and death certification process in place during Hurricane Maria. Interviews at the governor’s central communications office revealed there was no written plan in case of a disaster. Government officials said they had no knowledge of a coordinated plan between the health department and public safety department to report deaths.

Instructional materials about death certification did not tell providers how to handle deaths in the event of a disaster. And so many deaths that were related to the damage from the hurricane were not recorded as storm-related, complicating efforts by officials to identify Maria’s death total.

John Mutter, a professor at Columbia University who researches disaster management, said death certificates are “critical” to determining what is attributable to the hurricane. Mutter, who was not involved in the GW study, said specific death information can help researchers identify who died as a result of the disaster and who were the most vulnerable populations.

“It is the way we scale tragedy,” he said, noting that he believes the GW study is a good estimate.

The report offered recommendations on how Puerto Rico can improve its response systems, including updating communications plans and enhancing training for public health professionals. Those investments could prove tricky for the island, however, because its finances are controlled by a federally appointed fiscal control board.