Nine firefighters died last night in a Charleston, S.C., furniture warehouse-store fire. This is the largest number of fatalities in one incident since the Sept. 11, 2001, terrorist attacks.

“This tragedy is unimaginable. It is difficult to find the words to adequately express our sympathies to the families, to Chief Rusty Thomas and to the department of these heroic firefighters,” said Chief Jim Harmes, president of the International Association of Fire Chiefs.

“Even as we feel numb at this time, we recognize that when our firefighters are at work, things can change so quickly and dramatically that the unexpected can occur, as it did in this case,” Harmes said in a press release. “I am asking all fire departments, nearly 30,000, to respond to our request to recognize these firefighters, their families, their department and the community of Charleston by observing a moment of silence tonight beginning at 19:00 hours.”

South Carolina Gov. Mark Sanford has ordered South Carolina flags to be flown at half-staff.

“During this week of Safety Stand Down, we will remember these firefighters and honor them,” said Harmes.

The state’s LODD team, operated by the South Carolina State Firefighters Association and led by Fire Chief Butch Womack, has been mobilized and is on standby to give assistance. The Southeast Division of the IAFC has officers en route to Charleston to offer assistance.

The IAFC, the International Association of Fire Fighters and the National Fallen Firefighters Foundation are coordinating response efforts with the South Carolina State Firefighters Association and the South Carolina Fire Chiefs Association.