Protesters have blocked key roads around government buildings and threw bricks and projectiles at police.
The government is still pushing for the bill which would allow extradition to mainland China and it is expected to pass its final vote on 20 June.
But the Legislative Council (LegCo) has now delayed its second reading.
This is the first time rubber bullets have been used in Hong Kong for decades. 22 people have been injured so far but none are said to be critical.