Security 'tense' after deadly China attack

Security has been tightened in China's north-western region of Xinjiang after an attack on Thursday that left 31 people dead.

Two off-road vehicles drove straight into crowds of shoppers before several explosions were detonated in the city of Urumqi.

John Sudworth reports that the same region has seen a number of similar incidents in recent months - which have been blamed on Muslim extremists from Xinjiang's Uighur population.