WASHINGTON — Seven minutes after the authorities in Sparks, Nev., received a call one day in October that a gunman was on the loose at a local middle school, a paramedic wearing a bulletproof vest and a helmet arrived at the scene.

Instead of following long-established protocols that call for medical personnel to take cover in ambulances until a threat is over, the paramedic took a far riskier approach: He ran inside to join law enforcement officers scouring the school for the gunman and his victims.

“He met the officers right near the front door, and they said: ‘Let’s go. There are victims outside near the basketball court,’ ” said Todd Kerfoot, the emergency medical supervisor at the shooting. “He found two patients who had been shot and got them right out to ambulances.”

Federal officials and medical experts who have studied the Boston Marathon bombing and mass shootings like the one in Newtown, Conn., have concluded that this kind of aggressive medical response could be critical in saving lives. In response to their findings, the Obama administration has formally recommended that medical personnel be sent into “warm zones” before they are secured, when gunmen are still on the loose or bombs have not yet been disarmed.