Twenty persons were killed and two injured on Monday in a road accident in Pakistan's Sindh province, police said.A senior police official said the accident took place when an overloaded coal truck fell on a passenger van while trying to overtake it near Shah Hussain area in Khairpur district, reports Xinhua news agency.According to data released by the Pakistan Bureau of Statistics, around 9,000 road accidents were reported every year since 2011 in the country, killing more than 4,500 people on average annually.Traffic officials said that 90 per cent of the accidents in Pakistan are caused by human error.