Teen charged after trolley throw stand-off

A teenage girl who allegedly threw a shopping trolley at a shop and threatened to kill a staff member has been charged after a tense stand-off between police and a gang in Sydney's west.

Police were called to a Mt Druitt shop on Monday night after a 17-year-old girl allegedly threw the trolley and threatened the staff member.

Police say when officers arrived a struggle broke out as they tried to arrest the girl, while a group of 15 people surrounded and threatened the officers.

The officers radioed for back-up and a 27-year-old man had to be subdued with capsicum spray before he was taken with the girl to the station.

The teen was charged with multiple offences, including breaching bail and two counts of assaulting an officer, while the man was charged with wilfully obstructing police.