The ambulance crash is an accident that happened when a seizing paramedic crashed an ambulance into another ambulance.
While driving a patient to the hospital, Mary Daltrey had a seizure and crashed the ambulance into another ambulance, injuring herself and her partner, Shane, as well as the occupants of the other ambulance, Stan Giamatti and Ray Sutera, who were trapped hanging upside down. Jacob Nolston, the patient Stan and Ray had just dropped off, was injured by a piece of shrapnel that was embedded in his leg.
Callie, Bailey, and Meredith rushed to help the paramedics in the two ambulances. Bailey opened the back of the second ambulance and Shane said the patient started coding as soon as they picked him up and Mary had some sort of seizure. The patient was DOA and Shane refused to let Bailey check out his injuries, despite clutching his abdomen. Callie attended to Mary, who was unconscious and had a dislocated elbow. As the unloaded, Shane requested a male doctor.
In the ER, Shane continued to refuse to be examined, even after Richard came in. They deduced that he really wanted a white doctor. Not wanting to give in, Bailey requested Cristina. Cristina pulled up his shirt to examine him, revealed a large Swastika tattoo. After his exam, he was taken for a CT, which revealed internal injuries. He was told he needed surgery, but he refused to consent, believing Bailey would kill him. He wanted a white doctor present to ensure it wouldn't happen. Bailey recruited George and took Shane into surgery.
Mary regained consciousness in the ER and wondered why she had a seizure as she had no prior history. Derek ordered an MRI, which showed a tumor in Mary's brain. Derek decided to do minimally invasive surgery to remove it, so he could avoid opening her skull. While he was operating, there was a problem with the computer system, leaving the navigational system unusable, meaning he couldn't move the probe without risking damage to her brain.
Stan and Ray were still trapped when the firemen arrived to get them out. Stan told Richard he couldn't feel his legs and wondered if they were broken. His ears were also bleeding. He asked for them to get his wife, Sara, an x-ray tech at the hospital. Out of hearing range, Richard told Meredith to get Sara and told her that the moment they moved Stan, he would bleed out and all the medicine in the world wouldn't be able to save him. In order to keep himself conscious while he waited, Stan and Ray started singing, "I can see clearly now." Sara arrived shortly afterward and was able to say goodbye to him before they started to open the rig after Sara went back inside. AS they started to free them, Stan yelled for them to stop. Ray had an oxygen regulator stuck in his back, which caused cardiac tamponade. They started to check him out and noticed Stan had succumbed to his injuries. Meredith crawled into the ambulance to do an ultrasound to confirm Ray's condition. ("Crash Into Me, Part 1")
Shane's surgery was finished successfully, but he had a complication, so he had to go right back in. During the second surgery, he had several other complications, but he survived all of them. When Bailey finished, she sewed him up with his tattoo misaligned, which he believed she'd done on purpose.
Since the closest tech was five hours away, Derek asked Steve to go try to find anyone with any computer experience to help. Rose offered that she'd done three semesters of computer science before switching to nursing and might be able to help. She tried, but had trouble connecting wires as she said she didn't have the steadiest hands. Derek offered to do the work while she told him what to do. After the last wire was connected, the machine still wasn't working and Derek told Rose to think and figure out what she missed. She then realized she forgot to hit restart. Once she did, the machine worked perfectly and Derek was able to finish Mary's surgery.
Once ultrasound confirmed cardiac tamponade, they prepared for Meredith to do a pericardiocentesis to relieve the pressure on his heart. Once the blood was drained, they freed Ray and took him into surgery. Meredith ran into Sara and updated her on Ray. She also encouraged Sara to be there for Ray, because it's better to have someone even though it's painful. She was by his side when he woke up after surgery. ("Crash Into Me, Part 2")