>> chris barton. b. a. r. t. o. n.. [ indiscernible ] so as rachel said, we are -- the only level one trauma center in the city. serving san francisco and northern san mateo county. and i think what you've been observing here today is something that we practice for. we do lots of drills. lots of table top scenarios. and we run through this process repeatedly to make sure that we're ready. and i think what you saw in the response to the boston marathon is -- >> we're going to break away from the press conference at sf general where they're telling us now they had 34 patients. ten of those originally were in critical condition. now of those original ten. five. there has been some improvement. >> an update from news conference at sfo. let's go to that now. >> thank you. at this time we continue towork with the ntsb on determining the exact cause of the incident. there's currently and continues to be no indication that terrorism or any criminal act contributed to the enaccident. we are -- incident. we are offering all r

chris barton, head of the emergency room there, said we pulled out those tents.e set up the triage system already. we haven't used those tents, he said. but they're already ready with what's called surge capacity. david knows about this having done trauma training. you need a surge capacity where the emergency room can expand. and where the hospital has the ability to take care of patients it wasn't expecting. >> david, we have 49 people now in critical condition. obviously the focus is on them. talk about that surge capacity and what doctors are doing now for those? >> what really happens in a situation like this when you have a crisis, the doctors are not at the scene. you have the ems going over there. all the ambulances coming in from every angle, every hospital to be able to assess exactly what's going on. the first thing comes to mind is the abc they have to take care of. airway, breathing, circulation, making sure everyone is able to breathe. there's no active bleeding going on. they're securing the breathing. what we get, this is obviously in san francisc