A doctor who oversaw the New York City medical examiner's office for more than two decades and whose staff helped identify the remains of Sept. 11 victims has died. Charles Hirsch was 79.

Mayor Bill de Blasio (dih BLAH'-zee-oh) announced Hirsch's death Friday but didn't reveal the cause. He says Hirsch served as medical examiner for 24 years and was a dedicated public servant and talented medical expert.

Hirsch rushed to the World Trade Center on Sept. 11, 2001, and was hit by falling debris as the first tower collapsed. He oversaw the medical examiner's office as pathologists worked for years to identify the remains of the more than 2,000 victims.

The Democratic mayor credits Hirsch with making the office a "national leader in forensic pathology."

Hirsch retired in 2013.