In Jharkhand Four persons, including three policemen, were killed and six others injured when Maoists fired on a transit van ferrying prisoners and a police escort car to free their cadres in this town today at Giridih.According to police a group of around 25 Maoists, including women cadres, blocked the road with a truck at Udna More and fired on the transit van ferrying prisoners including Maoists back to jail from court, and the escorting police car.Police further said that there were 32 prisoners in all, eight of them being Maoists.The six injured policemen, including a woman constable, were hospitalised.Six bombs which failed to explode were recovered from the spot.