Man holed up in Western Sydney home after claiming to be armed

Police have surrounded a home in Sydney's west where a man is believed to be holed up after threatening government employees.

A by has been critically injured after being struck by an alleged drunk driver. Source: AAP

Police were called to Chopin St in Seven Hills about 10.30am on Thursday after a man allegedly threatened Department of Housing staff and claimed he was armed with a weapon, police told AAP.

When officers arrived, the man allegedly refused to let them in.

Negotiators are attempting to speak with the man.