It's emerged police in Texas waited for a key to the classroom door which a gunman had gone through - when it wasn't even locked.
Officials have been giving evidence to US politicians about officers' handling of the school shooting last month, which left 19 children and two teachers dead.
Texas' Public Safety Director Steven McCraw, says the response was an 'abject failure' - and that it could've ended within three minutes of the attacker going in.
