Heavily armed police arrest a number of people at a unit block in Arncliffe in Sydney's south

Armed police have stormed a unit block in Arncliffe, in Sydney's south, arresting a number of people.

Dramatic pictures show heavily armed police tackling a man to the ground and removing and arresting others.

Diversions have been put in place around the Princes Highway and Forest Road. 

It is unclear what the raid is over.

This is a developing story. More information will be added as it comes to hand.