The remains of a firefighter who died on Sept. 11, 2001 were recently returned to his family, allowing the man to be laid to rest one day before the 18th anniversary of the terrorist attack that killed 2,977 people.

Michael Haub was a member of Ladder Company 4, serving in the Fire Department of New York for 13 years, according to a statement from the Department's Uniformed Firefighters Association. Loved ones and firefighters attended his funeral Tuesday.

A spokeswoman with the New York Office of Chief Medical Examiner confirmed to USA TODAY that although Haub's remains were identified years ago, they were only recently returned to Haub's family, allowing them to hold a proper memorial service.

About 40% of the 2,753 people who died at the World Trade Center remain unidentified. 1,644 people killed at the World Trade Center have been identified by the medical examiner's office and 1,109 remain unidentfied.

Forty additional people lost their lives when United Flight 93 crashed in Shanksville, Pennsylvania and 184 people died in an attack at The Pentagon.

"May Firefighter Haub rest in peace and may today’s service finally provide his family the closure and peace of mind that Michael is at rest," said Gerard Fitzgerald, president of the Uniformed Firefighters Association in a statement to USA TODAY. "Firefighter Michael Haub is a hero."

'We are united':US marks 18th anniversary of 9/11 terror attack with silence, tolling bells

In addition to the 343 FDNY firefighters who died in the terror attacks on Sept. 11, hundreds more have died from illnesses linked to 9/11 in the years since. Twenty-two names were added Wednesday to the FDNY World Trade Center Memorial Wall in Brooklyn to honor those who have died this year from these illnesses.

The Centers for Disease Control and Prevention estimates that 400,000 people were exposed to toxic contaminants, physical and emotional stress, and injury risks in the months following the attack.

First responders exposed to the 9/11 terrorist attacks have been affected by PTSD, asthma and may have developed cancers such as leukemia and lymphoma.

Contributing: Olivia Sanchez, USA TODAY. Follow Joshua Bote on Twitter: @joshua_bote