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Police are investigating the assault of a 77-year-old man in his Wentworth Falls home during a break-in on Wednesday night.
Emergency services were called to the home on Maple Grove just after 8pm on February 6 after the man's wife found him tied up and injured in the garage. It is believed the man was assaulted about two hours before he was located.
He was taken to Nepean Hospital with head injuries.
Blue Mountains Police have established a crime scene which is being examined by specialist forensic officers.
A number of registered firearms are believed to have been stolen from the garage.
Detectives have appealed for anyone who may have seen suspicious activity in or around Maple Grove to call Crime Stoppers on 1800 333 000.