CCTV footage shows the moment more than a dozen masked robbers carried out a smash-and-grab raid at a jewellery store in California - with the store's 88-year-old owner knocked to the ground.

The pensioner was taken to hospital where doctors said he also suffered a stroke during the ordeal, his niece told Sky News' US partner network NBC News.

The footage shows a grey Ford Explorer SUV pull up outside the Kim Hung Jewelry store in San Jose on Friday afternoon before reversing through the glass front of the store at speed.

The vehicle then drives out of the shop and stops nearby before three more cars pull up outside.

At least 15 suspects, wearing hoodies and masks, then get out of all four of the vehicles before running inside the store and stealing jewellery after using pick axes and

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