At least eight persons were killed and nine injured on Monday in an explosion in a petrochemical plant in China's Shandong province, police said.A liquefied gas tanker exploded around 1 a.m., causing a fire in the loading area of Linyi Jinyu Petrochemical Company, Xinhua news agency reported.Police have detained the owner of the company.More than 900 firefighters and over 170 fire engines were mobilised to extinguish the flames, with people in nearby areas evacuated.