Residents may have noticed a large police presence at Westfield Trumbull mall last Sunday evening, complete with specialized tactical team vehicles. The good news is there was no emergency or disaster — but officials were training for one.

Trumbull police, working with FBI and Connecticut State Police, staged a large-scale training exercise, simulating a complex attack, at the Westfield mall, after hours.

This was one of the first drills the FBI is conducting statewide and nationwide as part of a final phase of the “Complex Mall Attack Initiative” to promote preparedness.

“It’s the first time I can remember, in 40 years, that we had federal, state and local officials working on a large-scale drill at one time,” police Chief Thomas Kiely said. “It brought up communication issues we would encounter during a big event, it brought up logistical issues and what is going to work in a setting like the mall.”

Trumbull Deputy Chief Glenn Byrnes, who worked with the FBI’s New Haven field office to facilitate the exercise, said the exercise involved roughly 150 people, and several police vehicles and resources.

“Emergencies of such a proportion, there are many more assets that come into play that are not used on a regular basis,” Byrnes said. “Drills like this allow us to get familiar with the resources.”

Byrnes said the Trumbull police and the town’s Office of Emergency Management work regularly with Westfield mall, though this exercise was unique.

“We have worked with the mall for many years now and emergency management has worked with the mall to ensure all precautions are taken on a regular basis,” Byrnes said. “This was going well beyond that. The mall is one of our biggest areas of concern with the largest population at any given time. By working together it prepares us for any type of event.”

The Southwest Regional Emergency Response Team, a SWAT force of officers from Trumbull, Easton, Monroe, Wilton, Westport, and Darien, was part of the exercise, along with state police and an FBI team out of New Haven. Bridgeport police also assisted with the exercise. The Long Hill Fire Department’s chief, Doug Bogen, participated, along with Trumbull EMS Chief Joe Laucella. EMS posted an ambulance outside the mall during the training.

“We set up a full command post at headquarters,” Kiely said. “We were in communication with New Haven and Washington.”

At headquarters, Chief Kiely, FBI New Haven Division Special Agent in Charge Patricia M. Ferrick and state police Maj. Brian Meraviglia were in constant contact with the team at the scene. The scenario involved several aspects that the team was confronted with, including defusing a bomb, Kiely said.

“In the event of a crisis, we will be prepared,” Ferrick said in a press release on the exercise. “The ability to respond with our local, state, and federal law enforcement agencies, first responders, and private sector partners to a realistic multifaceted scenario is absolutely critical to our mission. Training with our partners and then assessing our strategies and actions to improve upon our overall response is the very definition of preparedness. We are sincerely grateful for the effort and planning from all of the participating agencies and look forward to future training collaborations.”

“The Connecticut State Police prides itself on preparedness because so often we are among the first responders to a crisis,” said Maj. Meraviglia. “It is vitally important for us to continue to train with our local and federal partners, and this tactical training exercise afforded us that opportunity. I wish to thank everyone involved in the extensive planning that went into putting on this most worthwhile endeavor.”

The exercise took a lot of planning with Westfield. The exercise happened after hours on Sunday, and Kiely praised the mall staff, including manager Pat Madden, for being so accommodating.

“We want to thank the New Haven FBI, the Trumbull Police Department, the Connecticut State Police, and fire and emergency services, as well as local officials, for their ongoing efforts to create lasting partnerships and for their dedication to public safety,” said Christopher Powers, assistant general manager at the Westfield Trumbull shopping mall.

Kiely said the training was invaluable in pointing out potential weaknesses and coordinating efforts.

The FBI.gov site offers an “Active Shooters and Mass Casualty Incidents” information page as a resource for the public and law enforcement to learn more about critical incidents.