For the second time yesterday morning, I found myself lying face-down on a garbage bag, head turned just enough to see an armed SWAT team running through the door.

"Are you okay?" one of them yelled, grabbing my wrist.

He paused, and then let it drop.

"DOA!" he called to the other Alameda Police Department officers, and they ran from the room.

I was inside Urban Shield, the largest police tactical training event in the nation. For 48 continuous hours last weekend, more than 20 departments neutralized scenarios across the Bay Area ranging from terrorism threats to natural disasters and prison breaks.

Berkeley police and UCPD held an active shooter simulation on the UC Berkeley campus.

I became that scenario's "designated dead body," lying in a metal pod in a building on Berkeley Way that used to house animal research projects.

Then I was whisked down the building's stairs and resurrected as a hostage in the final shoot-out scene. I sat with my fellow-hostages on one side of a darkened lecture hall. On the other side, seven scarecrows in baseball caps sat smiling at us from across the aisle.

We waited.

As the SWAT team neared, gun shots sounded, and the instructors told us to scream as if we were being executed.

The shooter stood in front, holding a hostage across the chest. About six SWAT team members rushed into the room, firing at the shooter over the scarecrows' heads, and neutralized the threat.

During the scenario, the teams shot guns loaded with capsules of brightly colored soap resembling paintballs.

"But it hurts more than a paintball," said UCPD police Lt. Adan Tejada. "It'll raise a welt and probably break your skin."

Only role-playing police officers were supposed to be in the line of fire. But after a team has endured more than 24 hours of simulation on about an hour of sleep, the "fatigue factor," as officers called it, begins to set in.

An Alameda police officer shot Emeryville resident Nick Whiting, 25, in the chest during one round, leaving a bullet-shaped hole in his shirt.

"It was a pretty good sting," Whiting said, pressing an ice pack on the spot. "And there was soap in the wound. It took three or four scrubs to get it out."

Organizers modified the scenario after the incident to avoid direct confrontations between the volunteers and the SWAT teams.

Despite a risk of mild injury, the event attracted a number of walk-on volunteers Sunday afternoon.

Kevin Lee, a fifth year UC Berkeley student, said he saw a bunch of police officers standing outside a building as he rode by on his motorcycle. He decided to join the event and quickly found himself crouched in a stairwell, awaiting a signal to run toward the Oakland SWAT Team.

"When you do something once, it prepares you for the second time," he said. "If it really happened, you'd think twice before doing something stupid."

Tags: URBAN SHIELD