We report the observation of an intense gamma‐ray burst observed on the ground at sea level, produced in association with the initial‐stage of rocket‐triggered lightning at the International Center for Lightning Research and Testing at Camp Blanding, FL. The burst was observed simultaneously on three NaI(Tl)/photomultiplier tube detectors that were located 650 m from the triggered lightning channel with gamma‐ray energies extending up to more than 10 MeV. The burst consisted of 227 individual gamma‐rays that arrived over a 300 μs time period in coincidence with an 11 kA current pulse. The burst of gamma‐rays had very different characteristics from the x‐ray emission frequently seen in association with the dart leader/return stroke sequences of triggered lightning and may represent a new kind of event, likely originating from cloud processes thousands of meters overhead.
