An account administrator at a securities firm was working overtime in a section of a vault. At 7:10 p.m., security personnel closed and locked the vault. The employee was working in a section of the vault accessible only with a swipe card. The security guard did not have a swipe card and did not access that area of the vault, but instead looked through a small window and apparently did not see the employee. The employee discovered that the vault was locked shortly thereafter. There was a phone in the vault, and the employee apparently tried unsuccessfully to call for help. At about 7:35 p.m., the employee pulled a manual fire alarm system actuation device. In addition to sounding an alarm, the device instantly activated a total flooding CO2 fire-extinguishing system. Activation of the CO2 system created an atmosphere immediately dangerous to life and health inside the locked vault. Using self-contained breathing apparatus (SCBA), firefighters recovered the employee’s body. The cause of death, as ruled by the medical examiner, was accidental CO2 intoxication.