This evening while Chief 10 was enroute to Prince Frederick for a county meeting he heard the CCSO call out with a serious MVC on Rt-4N @ HG Trueman Rd. On scene officers were reporting a T-bone style accident with one occupant in the car with agonal breathing. A CCSO officer who is also a MD EMT immediately reached into the vehicle and performed a rapid trauma assessment, and requested a pre-alert of MSP aviation. Chief 10 was only 2 miles from the call when it was dispatched and arrived on scene as the first fire department unit. M103(PMIC M.Gill) marked up responding from the office in Prince Frederick as the 2nd medic. Chief 10 along with the CCSO deputy devised a plan to rapid extricate the pri-1 patient and move her into A77. Solomons A38 who was transporting a patient to the ER in Prince Frederick from a previous medical call with a medic on board stopped to make sure units on scene did not need any assistance. Once confirmed that no other resources were required A38 continued on with their transport. Past CALS Chief P. Lenhar was on his way home and came across the accident and assisted Chief 10 and the crew from A77 with patient assessment and packaging. M103 arrived and checked with Chief 10 confirming no other assistance was needed then assessed all the other patients that were on scene. The patient was quickly packaged and was ready for transition as soon as MSP trooper 7 arrived. Due to the severity of the crash CCSO had shutdown Rt-4N, MSP trooper 7 landed in the northbound lanes just in front of the crash. The patient was quickly transfered to MSP and transported to a local trauma center with severe injuries.