End of game situation

[ref83]

There is 1 second remaining in the 4th quarter. Team A is up by 1 point. Team A is inbounding the ball in their front court. They throw the throw in pass deep into their back court. As the ball is in the air on the throw in, the horn sounds and the players assume the game is over and do not go after the ball which rolls out of bounds untouched. (Clock operator started the clock before the ball was touched inbounds.) Is the clock reset to 1 second? Is this ruled a throw in violation by team A? Thus, would team B be given the ball for a throw in at the same spot team A violated?