FORT DRUM — Fire and police agencies from throughout Jefferson County responded Tuesday morning to a mock terrorist attack on an idle airplane and fuel tanker at Wheeler-Sack Army Airfield.

The terrorists, plane and injuries all were fake; the response, however, had to be real. Fort Drum held an annual "anti-terrorism and mass casualty" exercise to hone the response of the county and post if an actual attack does occur. Because there are no hospitals on Fort Drum, the surrounding county agencies are involved in the exercise to help transport and treat victims.

During the exercise, the post raised its threat condition to Delta, its highest level. Roads and entrances were blocked off for several hours and military police rerouted traffic, said Benjamin E. Abel, Fort Drum media relations officer.

Standing on South Washington Street in the village of Carthage, rescue personnel shielded their eyes as a Black Hawk helicopter lowered itself onto a small helipad. The bird's payload included three soldiers in need of treatment from the "attack."

While members of the Carthage/Wilna Fire District blocked traffic, a Carthage Area Rescue Squad ambulance maneuvered its way to the helipad. After pulling three "burn victims" from the helicopter, the ambulance raced to Carthage Area Hospital.

Another Black Hawk was sent to Samaritan Medical Center, Watertown, with more victims.

"This is something new, and the exercise allows us to work with the helicopter crews," said Kris Kirkpatrick, Carthage Area Rescue Squad emergency medical technician. "I think we did pretty good as far as the helicopter is concerned."

The EMT said he's loaded victims onto smaller helicopters, but he's never taken victims from a larger Black Hawk and driven them in an ambulance.

The soldiers were sent through a decontamination tent erected outside the hospital, then rushed into the emergency room.

"We want to do this now so it's second nature if something does happen," said Thomas E. Jaconski, Carthage Area Hospital emergency management coordinator. "We want everyone on both ends to know what's going on."

A numberof emergency services personnel participated in the drill, including Fort Drum Emergency Services, the post's Incident Command Center, state police, Jefferson County Sheriff's Department and other local agencies.

The post set up an operations center at the Rapid Deployment Facility at Wheeler-Sack Army Airfield. The base, a windowless room overcrowded with people and computers, acted as response center, Mr. Abel said.

Fort Drum's response to the exercise was "top-notch," County EMS Director Charles F. Brenon III said. "They are well-prepared and well-trained."

Mr. Brenon said the exercise gave emergency personnel a chance to use the statewide Health Emergency Response Data System, which links responders with hospitals. The system gives information about area hospitals, such as the number of available beds for victims and the types of care each can provide.