  Feedback-driven winds from star formation or active galactic nuclei might be
a relevant channel for the abrupt quenching star formation in massive galaxies.
However, both observations and simulations support the idea that these
processes are non-conflictingly co-evolving and self-regulating. Furthermore,
evidence of disruptive events that are capable of fast quenching is rare, and
constraints on their statistical prevalence are lacking. Here we present a
massive starburst galaxy at z=1.4 which is ejecting $46 \pm 13$\% of its
molecular gas mass at a startling rate of $\gtrsim 10,000$ M$_{\odot}{\rm
yr}^{-1}$. A broad component that is red-shifted from the galaxy emission is
detected in four (low- and high-J) CO and [CI] transitions and in the ionized
phase, which ensures a robust estimate of the expelled gas mass. The implied
statistics suggest that similar events are potentially a major star-formation
quenching channel. However, our observations provide compelling evidence that
this is not a feedback-driven wind, but rather material from a merger that has
been probably tidally ejected. This finding challenges some literature studies
in which the role of feedback-driven winds might be overstated.
