The FBI says one of its first responders to the September 11, 2001, terror attacks has died of brain cancer linked to exposure to contaminants.

Special Agent Melissa S. Morrow died Thursday at the age of 48. She had served with the FBI for 22 years and was assigned to the Kansas City Field office when she died.

The agency said in a statement on Friday that Morrow made the 'ultimate sacrifice'.

Her death has been classified as a line-of-duty death, due to her exposure to chemicals responding to the Pentagon after 9/11, and a fire at an evidence warehouse in Alexandria.

Special Agent Melissa S. Morrow died Thursday at the age of 48. She had served with the FBI for 22 years and was assigned to the Kansas City Field office when she died.

Her death has been classified as a line-of-duty death, due to her exposure to chemicals responding to the Pentagon after 9/11 (pictured)

The warehouse contained evidence from the Pentagon attack and caught fire in 2013.

Prior to serving in Kansas City, Morrow was a member of the Evidence Response Team in the Washington Field Office.

She spent 10 weeks recovering and processing evidence from the 9/11 attacks.

She had been certified by the World Trade Center Health Program and the September 11th Victim Compensation Fund.

Morrow spent 10 weeks recovering and processing evidence from the 9/11 attacks

Morrow joined the FBI in 1995. Her funeral will be held at Country Club Christian Church in Kansas City on Tuesday afternoon.

It comes less than a week after a former firefighter who evacuated hundreds of people from Lower Manhattan during the September 11 attacks died of cancer at the age of 45.

Thomas Phelan, who was working as a ferry captain when he helped evacuate survivors, died on March 16.

His illness was also believed to be related to exposure to the toxic fumes swirling around Ground Zero.