Hyderabad, Oct 1: At least 50 passengers were feared drowned when a private bus in which they were travelling plunged into a rivulet at Inaganur village of Tondur Mandal, Cuddapah district, tonight. Twenty persons including bus conductor Krishnudu managed to break open the windowpanes and extricate themselves from the bus, when the reports last came in.The bus was going to Muddanur from Pulivendula when it crashed into the railing of the causeway and fell into the rivulet. Water was flowing five feet above the causeway and the vehicle driver unmindful of the danger in store for them drove the vehicle resulting in the mishap. The visibility was also poor due to the heavy rain that had been lashing the area since evening.Cuddapah District Collector, senior police and revenue officials rushed to the spot. A team of armed reserve constables and medical personnel also reached there. The monsoon-swollen rivulet is flowing rapidly and heavy rain and complete darkness have been hampering the rescue operations.The escaped persons were taken to Tondur police station, two kilometres away from the accident and first aid was extended to them. None were hospitalised so far.Police and revenue officials have been alerted and policemen were posted down the stream to rescue those who are being washed away. Last year at the same spot in a similar accident 80 persons died. Meanwhile, Transport Minister K Chandrasekhara Rao left for the accident spot. Chief Minister N Chandrababu Naidu who expressed shock over the mishap has directed the minister to supervise the rescue operations.Congress Legislature Party leader P Janardhan Reddy also expressed shock.