A New York City firefighter who helped thousands of people in Lower Manhattan on September 11 has died.

Thomas Phelan, 45, died on Friday from cancer. According to the Daily News, officials and his friends believe the toxic fumes at Ground Zero were linked to his cancer. According to the Uniformed Firefighters Association of Greater New York, Phelan was the 172nd firefighter to die as a result from an illness related to the attack.

Phelan was working as a Statue of Liberty ferry boat captain when the planes hit the World Trade Center and left thousands of people stranded. In what has been described as the largest evacuation in city history, he turned his boat into a rescue boat. According to the Fire Wire Facebook page, “He brought supplies, rescue workers and was a huge part of the operation.”

Later in 2003, he joined the Fire Department of New York and was stationed in Little Italy before being promoted. Paul Iannizzotto, who work in the same station in Little Italy, posted on Facebook that Phelan was “always a stand up guy, always doing the right thing and will be sorely missed. Rest easy brother.”

New York City Mayor Bill De Blasio tweeted, “In our city’s darkest hour, @FDNY firefighter Thomas Phelan’s heroism saved hundreds of lives. We will never forget his service and his sacrifice.”