  The onset of galaxy formation is thought to be initiated by the infall of
neutral, pristine gas onto the first protogalactic halos. However, direct
constraints on the abundance of neutral atomic hydrogen (HI) in galaxies have
been difficult to obtain at early cosmic times. Here we present spectroscopic
observations with JWST of three galaxies at redshifts $z=8.8 - 11.4$, about
$400-600$ Myr after the Big Bang, that show strong damped Lyman-$\alpha$
absorption ($N_{\rm HI} > 10^{22}$ cm$^{-2}$) from HI in their local
surroundings, an order of magnitude in excess of the Lyman-$\alpha$ absorption
caused by the neutral intergalactic medium at these redshifts. Consequently,
these early galaxies cannot be contributing significantly to reionization, at
least at their current evolutionary stages. Simulations of galaxy formation
show that such massive gas reservoirs surrounding young galaxies so early in
the history of the universe is a signature of galaxy formation in progress.
