Four persons, including two women, were killed on Monday in a road accident on the Yamuna Expressway in Uttar Pradesh, police said.The accident took place at Greater Noida, seven km from the zero point.Apparently blinded by the fog, an Alto car rammed into a stationary tractor trolley from the rear. The deceased were identified as Manoj Kumar (53), Soni Sinha (50) - both residents of Ghaziabad, Usha (73), a resident of Patna, Bihar and driver Sultan Ahmad (40), a resident of Jamia Nagar, New Delhi.An official told IANS that Manoj Kumar was a senior official with the Cement Corporation of India and was returning from Bihar after attending a wedding along with his wife and mother-in-law.