WICHITA, Kan. (AP) — The FBI says one of its first responders to the Sept. 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.

The agency said in a news release Friday that Morrow made the “ultimate sacrifice,” and her death has been classified as a line-of-duty death. She had been certified by the World Trade Center Health Program and the Sept. 11th Victim Compensation Fund.

Morrow joined the FBI in 1995 and worked at its Washington field office prior to transferring to the Kansas City field office.

She was a first responder to the Pentagon crash site and the Alexandria evidence warehouse. The FBI says she spent 10 weeks recovering and processing evidence at the site.