Two bomb blasts in quick succession rocked Sankatmochan temple and the cantonment railway station here this evening killing at least 12 people and injuring over 20, some of them seriously.Immediately after the blasts, police was put on high alert in several parts of the country with security being beefed up at places of worship, vital installations and government buildings.The first blast took place inside the famous Sankatmochan temple adjacent to Kashi Vishwanath temple when it was teeming with devotees at the evening aarti killing four persons on the spot.Minutes later at 6:25 PM, another blast took place at the holding area of platform number one of the Varanasi Cantonment railway station when the Delhi-bound Shivaganga Express was stationary.Condemning the explosions, Prime Minister Manmohan Singh today appealed to the people to maintain calm."The Prime Minister has appealed for maintaining peace and calm. He is constantly monitoring the situation. He has condemned the blasts," PM's media adviser Sanjaya Baru said.