Police are investigating after a man was injured during an armed robbery at a café overnight.

About 1.30am (Sunday 16 June 2013), three masked men entered a café on High Street, Kensington, and threatened six staff members with sledgehammers and a crow bar, demanding cash.

As the store was closed, staff were unable to access cash. One of the men assaulted a 24-year-old male staff member with a sledgehammer.

The men then took personal belongings from the staff, including wallets and mobile phones, before running from the store.

The men were last seen driving east on High Street in a black Nissan Skyline.

Ambulance Paramedics treated the 24-year-old staff member for bruising and possible fractures to his shoulder and arm before taking him to Prince Of Wales Hospital.

Police from Eastern Beaches Local Area Command attended and established a crime scene, which was examined by specialist forensic officers.

The men have been described to police only as having olive complexions and speaking with an accent.

At the time of the incident, the men were wearing dark hooded clothing and ski masks.