A "low intensity" blast took place in a Haryana Roadways bus in Kurukshetra district on Thursday, injuring at least 12 passengers, police said. The state-owned bus was on its way to Chandigarh from Sonipat and when it reached Pipli area, the blast took place in it, police said. At least 12 passengers were injured in the incident, police said. The injured had been hospitalised at a hospital in Kurukshetra, police said. The cause of the blast is yet to be ascertained, police said, adding that forensic experts have been summoned. Police have registered a case and started investigations.