"I’ve never seen anything like this in my life--a ‘war zone’ of immense destruction with seven World Trade Center buildings completely destroyed and four other buildings damaged covering four blocks square," said Richard Tomasetti, President of Thornton-Tomasetti Engineers of New York.

Mueser Rutledge Engineers is evaluating the WTC substructure, which previously housed seven stories of transit, shopping, and parking to determine whether flooding and debris are undermining neighboring structures.

"There’s no way to minimize what happened here," said John F. Hennessey III, Chairman of Syska & Hennessey, whose firm is now undertaking mechanical/electrical engineering recovery work in both NY and at the Pentagon. Hennessey is also chairman of the Salvation Army of NY and heading up their relief drive.

Wilbur Smith Associates is assessing the structural integrity of the U.S. Drug Enforcement Administration headquarters building across from the Pentagon blast area.

Immediately after the attack, ACEC President David Raymond offered support and assistance to FEMA director Joseph Allbaugh, as FEMA mobilized assets around the country. Several ACEC member firms are under contract to FEMA for recovery work. ACEC members in NY and DC are also providing assistance to EPA and other federal and local government agencies.

While the disaster was of enormous magnitude, it could easily have been even greater if the WTC towers had toppled rather than imploded, according to Weidlinger Associates’ founding partner, Matthys Levy, coauthor of Why Buildings Fall Down. He said in the New York Times that the WTC’s collapse was an "uncontrolled demolition" that behaved "like a controlled demolition project," thereby sparing thousands of additional lives.