Automobile accidents are the most common, but other examples are airplane, buses, motorcycles, etc. Slip or trip and fall. Injury from defective products or medical devices. Negligence of a professional.
Medical malpractice is the most common but architects, engineers, lawyers, accountants, etc.
Call the police. Exchange identification and insurance information. Get names, address and telephone numbers of any witnesses. Secure medical attention for any injuries. If you suffer a fall or other injury, be sure to report it to those in charge.