NEW DELHI (Agencies) - India on Monday expressed sadness over the loss of lives in the terror attack in Karachi and issued an alert to all the states in its aftermath to step up vigil. Indian Home Minister P Chidambaram said the attack on Pakistan Navys air base has once again highlighted the fact that India lives in a troubled neighbourhood. I have described our neighbourhood as a troubled neighbourhood. This incident once again points to that conclusion that our neighbourhood is a troubled neighbourhood, he said at a press conference here when asked to comment on the attack in Pakistan. He said India was not happy about the incident that took place in Karachi. In fact, we are sad that lives are lost. But that (Pakistan) is today a troubled State. Meanwhile, India is concerned about the safety of nuclear facilities in Pakistan. 'We are concerned with the safety of Pakistans nuclear installations, senior officials, travelling with Indian Prime Minister Manmohan Singh, said in Addis Ababa. 'The real risk is internal - who guards the guardians, the Indian officials said.