Just after 9 a.m., during the change between classes, the mock incident began.
The scenario involved a chemical spill or spray of unknown origin in the hallway at Hermosa Middle School. San Juan College actors played the possible perpetrators or victims exposed to the chemical during the event.
The school was promptly evacuated and roughly 500 students and school officials walked across the street to nearby Northeast Elementary and a lockdown was ordered.
The drill ended two hours later, shortly after 11 a.m., and involved the coordination and participation of the Farmington fire, police, and emergency medical personnel. Navajo Nation police, San Juan Regional Medical Center, San Juan Office of Emergency Management, and San Juan County Sheriff's and Fire departments also participated.
This planned emergency exercise is the district's 14th of the school year, said Assistant Superintendent of Campus Programs Frank Stimac.
The district's bus barn was put on alert and three student head counts were made over the course of the exercise.
"It's one thing to do one of these exercises during class, but it's another when it's between classes," Stimac said. "It went very well today. We're working hard to refine things, emphasizing communication and accountability.
The Farmington School District has video cameras in all of its schools and has put in place more than 500 two-way radios so teachers can directly call police dispatch in the event of an emergency, Stimac said.
"It's vitally important to practice facing these types of emergency events - whether they are fires, of chemical origin, involving firearms or a situation of domestic violence that moves on campus," he said. "The big thing we learned was communicating with each other and the various agencies to always ensure that every child is safe and accounted for."
Each school has its own safety plan, but a directive from Homeland Security four years ago recommended schools keep knowledge of the specific processes and protocols limited to school officials.
Farmington Fire Department Battalion Chief David Burke participated in the Friday drill and sees progress in the schools' responses to the challenges that each unique drill presents.
"With every drill we test the schools on their ability to account for all of their students and I have personally seen a great improvement made over the last year," Burke said. "I can say with confidence that because of the leadership from the police department, and working with all agencies, that we are at the forefront for this kind of preparatory work."
The schools will follow up with students on their reactions and ideas based on their drill experience sometime after spring break, Stimac said.
"Every parent is informed by the school that the No. 1 priority is the safety of each child, but the specifics on a safety plan remains in-house for good reason," he said. "After the drill we (school officials) gathered together and de-briefed for close to two hours on what we learned and ways we can make our operations better."
The recent tragedy at Sandy Hook Elementary has not directly impacted the district's approach to emergency preparedness, Stimac said.
"The shooting at Newtown, Connecticut, invariably changes everybody's thinking - it definitely heightens the awareness," he said. "But we've been committed to this all along."
Overall, Stimac regards Friday's latest exercise as a success that will lead to better practices down the road.
"We've come a long way," he said. "We have the wonderful support and working relationships with our fire and police personnel and all the other agencies who play such a critical role to help keep our students safe."
James Fenton can be reached at email@example.com; 564-4621. Follow him on Twitter @fentondt