Are your community's paramedics trained to integrate with law enforcement rescue teams and to save lives before the scene can be "totally secured?" If not, you should be.
This is not a "SWAT medic" question. The lesson from Columbine is "if you wait for SWAT, people will die." Law enforcement has evolved a new doctrine for active shooters.....go to the sound of the guns, and neutralize the killers. And it's not for senior officers and special units - the success of the response to an rapid mass murder event is dependent on the skills, training, and physical condition of every police officer and EMS medic on the street.
EMS medics can be integrated in to LE rescue teams with a relatively high degree of safety, allowing live-saving measures (like tourniquets) to be utilized before it is too late. But it takes policy, training, communications, and cooperation to make it work.
Here, during a training exercise, City of Raleigh police officers provide security for Wake County EMS system medics conducting rapid assessment, treatment, and casualty collection evolutions. http://legeros.com/ralwake/photos/2011-07-13-ems-active-shooter/sli...
It CAN be done. It SHOULD be done. EMS has to be trained, equipped, and expected to move-communicate-assess-treat while protected by responding LEOs. It won't happen by accident - it requires planning and communication.
It's time to get started!
I don't know the stats to back this up, nor do I know where to get them (although the FBI UCR division might be able to offer some data), but what exactly is the risk in an active shooter incident once the shooter(s) are arrested, killed, or escaped? As was mentioned above, secondary searches take forever, while people bleed. What's the historical risk of secondary threats? My experience of reading the news (scary thought, I know!) is that once the shooter stops shooting, the threat of violence is essentially over. We need to be concerned with safety, certainly, but we also need to take a realistic look at the risk. There's a threat of violence on every EMS call; we make informed risk/benefit decisions on when it's safe to enter the scene. If the research shows that it's safe for EMS folks to enter the scene of a mass shooting once the shooting stops, then we need to be going in. (In the interest of full disclosure, I'm a tactical medic, but an unarmed one by department policy. So I'm not one to run after a gunman throwing pressure dressings to stop the shooting!)