By Al Novack

PHILADELPHIA (CBS) — In order to fine tune response by city emergency responders to a terrorist bomb explosion on or near the Broad Street subway, the Philadelphia Fire Department, city police, transit police and the FBI cooperated in a four-hour training exercise on Sunday.

The training drill was not announced in advance so as to surprise all responders.

According to Deputy Mayor for Public Safety Everett Gillison, the surprise exercise tests preparedness and cooperative communication abilities.

“This exercise is to test the integration and our operability, the decision making between both high level executives and also guys on the ground,” Gillison says.

The drill began totally unannounced with emergency management actors phoning 9-1-1.

After receiving the surprise calls, 9-1-1 operators dispatched responders to the drill site near Broad and Fairmount Streets.

Following the exercise, officials reviewed how the responders performed and picked out any flaws.