China's top leaders have urged "all-out efforts" to treat those injured in a car attack in southern China, one of the deadliest incidents in the country's recent history, as online posts asking what the attack says about Chinese society were censored.

The Zhuhai attack in which a driver in southern China ploughed his car into a crowd of people and killed 35 people, severely injuring dozens more, has put the spotlight on a recent spate of similar attacks in China.