A four-day event beginning at the Alameda County Fairgrounds Friday (Sept. 9) is expected to bring hundreds of first responders -- as well as protestors -- to Pleasanton.

Urban Shield is returning to the Tri-Valley for the second consecutive year. Hosted by the Alameda County Sheriff's Office, it consists of a vendor show and training exercise geared toward law enforcement and other emergency personnel. The event, which is in its 10th year, was held in Oakland before moving to Pleasanton.

Come kickoff next Friday morning, Urban Shield participants will take part in a two-day training exercise that encompasses 35 individual emergency response scenarios ranging from an active-shooter situation to the discovery of dangerous devices or materials.

As part of the exercise, participants will get an introduction to the latest technology being used in each scenario, and they'll debrief about how using that technology went afterward, according to the event website.

This year's Urban Shield will also zero in on earthquake preparedness through its "Yellow Command" exercise, which tests out emergency response in the event of a regional catastrophe.

In previous years, first responders have practiced how to implement response plans for a passenger train crash and a terrorist attack. Next weekend, they will test how to distribute bottled water to those affected by a hypothetical Bay Area earthquake.

"The event allows participating agencies a practical opportunity to evaluate their tactical team's level of preparedness and ability to perform a variety of intricate first responder operations," an excerpt from the Urban Shield website reads.

The vendor show will include distributors of everything from gamma radiation detection devices and tactical body armor to body cameras and guns. Representatives from corporations like Verizon, Motorola and Samsung will also take part.

First responder agencies throughout the Bay Area, as well some from outside California, will come to Pleasanton for Urban Shield. They will join eight officers from the East County Tactical Team, the shared SWAT team of the Livermore and Pleasanton police departments.

The Pleasanton Police Department has participated in Urban Shield since it started, according to chief Dave Spiller. Attendance is not mandatory, as agencies have to apply and space is limited.

For Spiller, Urban Shield provides an invaluable training opportunity that his department itself could not offer because of cost and labor limitations.

"It challenges members physically and mentally," Spiller said Wednesday. "It creates scenarios for the tactical operators where they're forced to deescalate scenarios, to problem solve. It's a training opportunity we can't replicate and I find a huge value in our participation."

While some like Spiller underscore the value of such training exercises, others want to see Urban Shield done away with.

A group called Stop Urban Shield plans to protest the event from 8 a.m. to noon Friday and is coordinating transportation for residents throughout California that want to go. As of press time Wednesday, more than 300 people had indicated they were attending the protest on the group's Facebook event page. The group has protested Urban Shield in prior years, as well.

In an explanation about the event, protest organizers wrote that their goal was to end Urban Shield for good.

"(Urban Shield) consists of extremely militarized policing trainings and war games that only seek to expand the power of law enforcement over our communities," an excerpt from the social media post reads. "As we continue to face and witness the increased militarization and violence of policing, we must resist programs like Urban Shield, and demand the resources that build our self-determination."

Stop Urban Shield and Alameda County Sheriff's Office representatives did not return a request for comment before press time.

Regarding Stop Urban Shield's stance, Spiller said he would be disappointed if Urban Shield ceased to exist. He added that the scenarios officers run through during the training exercise include practicing opportunities for deescalating situations and saving lives.

"SWAT in and of itself is not a life-taking deployment of our personnel -- it's a life-saving resource," Spiller said.

"(Urban Shield) is a large-scale opportunity for first responders to face what complexities we're experiencing throughout the country," he added. "No one wants to think anything bad is going to happen in Pleasanton, but as police chief I want our officers to be as prepared as possible, and that's why we participate."