An elderly couple have been stabbed inside their Northern Beaches home in Sydney.

Police were called to an address Warriewood just after 11am today where they found a male and a female suffering multiple stab wounds.

Both victims were taken via ambulance to the Royal North Shore Hospital in a serious but stable condition.

LIVE UPDATES: Putin orders strategic nuclear forces to be placed on high alert

A young woman has been taken into police custody.

Investigations into the incident are ongoing.