The skyline over Denver will be busy with military helicopters today, as the Colorado National Guard trains for its mission as a responder in the event of a biological, chemical or nuclear attack.

Civil Air Patrol volunteers will stage a disaster scene beginning at about 9 a.m., and some “victims” will be airlifted to Pepsi Center as part of the training, said Capt. Michael Odgers, spokesman for the National Guard.

About five helicopters will be used, UH-60 Black Hawks and CH-47 Chinooks, with guardsmen aboard, he said.

The training also will includes flights to and from Colorado Springs and Pueblo, with the exercise expected to wrap up about 5 p.m., according to Denver police.

The helicopter training over the city is similar to the day- and evening-long event last summer by active-duty military personnel that alarmed some residents when it began unannounced a few weeks before the Democratic National Convention.

Denver police announced the exercise Wednesday and urged media to publicize it.