The BSE Oil and Gas index fell by nearly 4%, and the Nifty Oil and Gas index plunged by over 3.4% intraday on Monday after global crude oil prices crossed $100 per barrel. Shares of state-owned oil marketing companies (OMCs) plunged sharply, with Indian Oil down by 7.2%, Hindustan Petroleum down by 8.6%, and Bharat Petroleum by 8.4%.