A rocket-propelled grenade or RPG was fired from the street that shattered the glasses at the Punjab Police's intelligence headquarters in Mohali, the police said on Monday. The police called it an RPG-like attack and termed the blast a minor one. "A minor explosion was reported at the Punjab Police Intelligence Headquarters in sector 77, SAS Nagar at around 7.45 PM. No damage has been reported. Senior officers are on the spot and an investigation is being done. Forensic teams have been called," the Mohali police said in a statement.