When the call for a “mass casualty incident” blasted through the radio Sunday night, Clark County fire captain Joe Geeb had no idea what was happening on the Las Vegas Strip, but he immediately began thinking about how he would run toward the bullets, the mayhem and the carnage while everyone else was running away.

He quickly donned his flak vest and the helmet designed to withstand rifle fire and gunshots. Then he paused as a group of armed police officers created a protective bubble around him and other firefighters. Moving as one, the team hurled itself into the center of the chaos.

“I knew the officers had my back, and I would have had theirs,” Geeb said. “We’re going to go in together, and we’re going to come out together.”

Fire departments traditionally have waited on the sidelines of shooting scenes until police declare it safe for medics to go in and treat victims. In some cases, including high-profile mass shootings, that resulted in wounded patients bleeding to death even though medics could have saved them with immediate aid.

 “We saw from the reports of how these people died and the lack of interaction with the police departments and we knew we had to fix that,” Clark County Fire Chief Greg Cassell said Thursday.

Cassell said police and fire agencies in Nevada have been working together since 2010 to develop concerted responses to critical incidents, but Sunday was the first time their years of training and drills deploying “rescue task forces” played out in real life, the Washington Post reports.