At least four people were killed early on Monday when a speeding truck hit the convoy of the Madhya Pradesh Assembly Deputy Speaker in Balaghat district, police said.The accident took place just after midnight when Deputy Speaker Hina Kawre was returning to Lanji from the district headquarters.The victims included a police Sub-Inspector, a Head Constable, a Constable and the vehicle's driver.Another police official was injured and was in critical condition, the police added.Kawre told the media on Monday morning that her vehicle had a narrow escape from being hit by the truck coming from the opposite direction.