Tyndall Air Force Base, located in Panama City on the coast of the Florida Panhandle, was fully evacuated Tuesday night, just before the Michael made landfall, said Air Force General Terrence O'Shaughnessy, commander of North American Aerospace Defense Command.

"Before the storm ever arrived we'd actually transferred command and control capability to another facility," O'Shaughnessy told Pentagon reporters.

Tyndall is a major facility for protecting the air space over the continental United States, US Virgin Islands and Puerto Rico.

The four-star general added that some Florida residents may have been surprised by the rapid growth of the storm.

"It really started as a tropical storm, and then it went to Category 1, then it was Category 2 and before you know it, it was Category 4," O'Shaughnessy said.

"Where that becomes a factor is with the evacuation of some of the local populations," he said.

"We haven't seen as robust of an evacuation response from the civilian population that we have seen in other storms."

O'Shaughnessy said 2,216 active duty personnel had been pre-positioned ahead of the storm, along with 32 helicopters, 240 high-water vehicles and 32 swift water boats.

Thousands of National Guardsmen were also at the ready.