  We present the detection of an unusually large transient gas absorption in
several ionized species in the debris disc star HD 37306 using high-resolution
optical spectra. We have been analysing a large sample of debris discs
searching for circumstellar gas absorptions aiming to determine the frequency
of gas in debris discs. HD 37306 stood out showing remarkably broad absorptions
superimposed onto several photospheric Ca ii, Fe ii and Ti ii lines. The
observed absorptions, unlike typical exocometary transits, lasted for at least
eight days. Here we analyse simultaneous spectroscopic and photometric data of
the event and evaluate different scenarios that might explain the observed
features. We conclude that the most likely scenario might be an exocometary
break-up releasing a significant amount of gas close to the star, producing an
occulting "ring"/"torus" shape.
