Nine years have passed since Al Qaeda orchestrated the deadliest attack ever on U.S. soil, claiming nearly 3,000 lives.
But reports from the New York State Health Department suggest the carnage may not have ended that day.
More than 800 responders to the World Trade Center ruins have died -- some, advocates say, from illnesses related to their heroic efforts. One advocate says the actual total of deaths is likely higher -- and growing.
The data is a sobering reminder of the human toll that the tragedy is still taking as the nation prepares to mark the ninth anniversary Saturday of the 9/11 attacks.
According to the New York State Health Department, 836 responders have died as of June 2009, the most recent year of data available.
But in the last year, health officials have only confirmed 813 deaths after reviewing death certificates, autopsies or medical records as of June 2010.
Health officials couldn't conclude that any of the deaths occurred as a result of their response to the attacks because the study was short-term.
Of the 836 deaths, more than 20 percent were deemed by health officials as "traumatic," including exposure to harmful substances or environments, car accidents or assaults. The other 80 percent were from illness, the study found.
But John Feal, founding president of the FealGood Foundation, a groups that advocates for 9/11 responders, said the study is flawed and obsolete because it doesn't keep track of responders who live in other parts of the country and that he knows of up to 80 responders who have died since the department stopped keeping track.
While lacking hard data, Feal believes that more than 900 responders have died -- a figured he called conservative.
"I still think the number is low. We cannot keep a national average; it's just impossible," he said.
"I can guarantee over the last nine years, someone from small-town America has died from 9/11-related illnesses when that small-town doctor didn't know what he was looking at," he added. "All the undocumented workers who went home, a lot of the Spanish workers, they went home and died."
While it's not clear how many 9/11 responders have died as a result of their exposure to the World Trade Center ruins, thousands who are living with illnesses they believe are linked to their exposure at Ground Zero are fighting in court for compensation.
In June, a judge approved a settlement with city officials that could pay up to $713 million to about 10,000 police officers, firefighters and construction workers who had complained of breathing and digestive problems, chronic coughing and thousands of other ailments they say were caused by the toxic air at Ground Zero.
Also, the House is expected to reconsider a bill that would provide free health care and compensation to 9/11 rescue and recovery workers who fell ill after working in the ruins.
In July, the $7.4 billion bill failed to win the two-thirds majority that was needed under the procedure that Democratic leaders used to bring up the bill to block potential amendments. The bill fell short, 255-159. The vote was largely along party lines, with 12 Republicans joining Democrats supporting the measure.
The legislation is named for James Zadroga, a police detective who died at age 34. His supporters say he died from respiratory disease contracted at Ground Zero, but New York City's medical examiner said Zadroga's lung condition was caused by prescription drug abuse.
Members of Congress from New York and New Jersey have been pushing such a measure for years.
Similar legislation is pending in the Senate.
"We're at nine years and it's hard to wrap my arms around it," Feal said. "Nine years without federal assistance. But we're going to get the bill passed."
Feal predicts that the number of 9/11 responders who have died from illnesses will soon surpass the number who died in the attack.
"The men and women who have died since, who were literally searching for their loved ones who were lost have died or are dying because of neglect, poor leadership and bad politics," he said. "Our federal government, they put politics before human lives. That's unacceptable."