The drill, timed prior to the start of football season, aimed to prepare stadium employees and first-responders for a disaster that would injure or kill dozens or even hundreds of people, university officials said.
Wednesday's exercise was a year in the planning, according to Dan Stober, director of the Stanford News Service. It simulated an explosion in the stadium during a football game.
The event, which brought out personnel from 20 local agencies, was a reminder of the kind of preparation public officials are now forced to engage in, in the aftermath of terrorist events such as the April 15 Boston Marathon bombing.
Wednesday's drill was closely guarded. For security reasons, reporters were not allowed inside. But the sights and sounds from outside the stadium gave hints of the kind of pandemonium staff and responders expect to find in a real incident.
As the mock fans arrived, staff inspected specially made-up bags of 210 volunteers to see what might slip through. As the football team entered the stadium, cheers went up in the stands. A recording of the Star-Spangled Banner blared from speakers, and the crowd roared.
The explosion sent up a visible amount of smoke. A warning siren whooped continuously as the volunteers acted out their roles and more than 100 red-coated stadium ushers hurried to help fans get out of the stands.
Emergency responders by the dozens quickly arrived in ambulances and fire trucks.
"When we invite people to football games, we want them to be able to be safe," Stober said, as more than 100 faux fans calmly exited during the noontime drill.
Inside, volunteer patients — made-up with realistic-looking blood and burns — were carried to triage areas and prepared for transport to hospital emergency rooms: heads were stabilized in neck braces; burn victims emerged bandaged; victims appeared in shock.
Outside the ticket office, a cheer went up as three fans emerged, apparently unscathed.
"Yay! You made it out alive!" a waiting group shouted.
"Wow. That was a close one!" a man said, seemingly surprised by what happened inside.
"You should've been drunk like us," a woman quipped.
But they conceded their roles could have been worse; inside, somebody had been "trampled," they said.
Covered in faux blood and real bandages, 15 people were transported to Stanford or Lucile Packard Children's hospitals, Stober said.
Unexpectedly, a real medical event happened during the drill. Responders transported a pregnant woman to an area hospital for treatment, dispatchers broadcast.
A few other people had medical issues, though it wasn't clear they were emergencies, Stober said.
But those cases carried an important lesson: Anything can happen at any moment, emergency responders said.
In all, 100 emergency personnel took part, Stober said.
Those included a dozen each from the Palo Alto police and fire departments. Three employees from the city's Office of Emergency Services also participated, spokesman Lt. Zach Perron said. Many of the victims and witnesses came from Palo Alto's Emergency Services Volunteer (ESV) program, said Kenneth Dueker, the city's director of emergency services. Palo Alto's Mobile Emergency Operations Center served as an auxiliary command post at the stadium and handled radio and computer communications.
Perron said the stadium drill provided a critical opportunity for the city to test out its disaster response.
"Full-scale exercises like these are a valuable way for us to test our operational procedures in a real-life environment. It affords us the opportunity to work closely with our partner public safety agencies and organizations to ensure that we're all ready to work together seamlessly in the event of a major critical incident," he stated in an email after the event.
"Advance preparation is of paramount importance. And although we always chalk-talk possible incidents and talk conceptually about our responses, full-scale exercises like these provide us the chance to actually perform the tasks we need to perform. Our department would be part of the core group of first responders to any major critical incident on the Stanford campus, so it is important for us to participate in drills like these."