Indian stock indices fell sharply at open on Wednesday amid escalating tensions in the Iran-US conflict. The BSE Sensex dropped nearly 809 points to 76,135.72 after opening at 76,471.32. While the Nifty 50 fell nearly 200 points, slipping below 24,000-mark. Meanwhile, oil prices surged to a near six-week high after the US and Iran exchanged overnight strikes.