UPDATE: One of three being treated after Tuesday's shooting released from hospital

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(UPDATE 3:31 p.m.) - Two of the three people being treated at Carilion Clinic remain at the hospital as of Tuesday afternoon. The third person has been released.

One patient is in serious condition, while the other is in good condition.

ROANOKE (WSLS 10) - The Emergency Department at Carilion Roanoke Memorial Hospital says it received three patients from the scene of the incident on Campbell Avenue Tuesday morning.

All patients were suffering from gun-related injuries.

One is in good condition, one is in fair condition and the third is in serious condition.

Norfolk Southern employees were recently cleared to enter and exit the locomotive shop after being evacuated earlier Tuesday morning.

Carilion Clinic is one of the only trauma centers in the region, which means most of the time, critical cases are sent there, as was the case Tuesday morning.

Carilion staff does lots of training to be ready for a mass-casualty situation, whether it's a shooting or a car crash.

Typically the hospital gets a call from the scene, giving the hospital as much information as it can to get ready.

Sometimes staff has two minutes to get ready or sometimes they have 10 or 15 minutes to get ready.

Patients are taken to the trauma bay, where a trauma team starts addressing life-threatening needs. Immediately making sure their airway is open, they are breathing and their circulation is intact. They can also bring in an x-ray machine and take them to the CT scanner as needed.

"To the naked eye to somebody who isn't familiar with this room, it will look like a mass chaos. It may be upwards of 30 people in this room at one time depending on how many patients end up in here," explained Sarah Beth Dinwiddie, with Carilion Clinic trauma services. "But everybody in this room has a specific job roller. There's a team leader for each patient that is here. And everybody works together on that team to take care of that patient and get them where they need to be."

From there, they determine where they need to go and Specialized care they need.  The goal is that within 20 minutes, they will have identified the majority of their injuries, especially the life-threatening ones and have a plan in place for that patient's care. That means the patient will be then taken to the operating room, emergency room or ICU to further address his or her injuries.

With gunshot wounds, you never know how much damage has been done. Carilion staff said sometimes a wound looks really bad and it's not life-threatening, but sometimes a gunshot doesn't look bad and it could be life-threatening.