NEW YORK ( TheStreet) -- Insurers assessing the impact of Hurricane Sandy are already expected to face roughly double the property and casualty claims of Hurricane Irene, which pummeled the Eastern seaboard just over a year ago. Eqecat, a risk-modeling firm that quantifies natural disaster claims for the insurance industry, said Monday that insurers might be on the hook for between $5 billion and $10 billion in claims as a result of Hurricane Sandy. The consultancy also said total economic damages may total between $10 billion and $20 billion, as a result of home and business flooding. At the high-end of Eqecat's estimates, Sandy may cost insurers roughly double the disaster-related payouts of Hurricane Irene. On the low side of Eqecat's estimates, claims would mirror payouts for Hurricane Rita, which hit the East Coast in 2005. TheStreetreported that as of early Tuesday morning, more than 7.5 million people are without power nationally after Sandy made landfall. It killed at least 16 people in seven states and is expected to move into western New York on Tuesday night and into Canada on Wednesday. The New York Timesreported 11 deaths related to Hurricane Sandy, including seven in the New York region. Lower Manhattan, where the New York Stock Exchange floor is located, was still largely without power Tuesday morning after energy company Con Ed ( ED) shut off most of the electricity in the area to protect electrical equipment from the massive storm surge caused by Sandy. In a press conference on Tuesday afternoon New York, Mayor Bloomberg said roughly 750,000 New Yorkers remain without power and that the city's public transit system of subways and buses remains suspended indefinitely. Late on Monday, the Metropolitan Transit Authority shut the New York subway system and MTA chairman Joseph Lhota said on Tuesday that widespread flooding makes Sandy the worst natural disaster in 108 years for the transit system. The New York Stock Exchange and Nasdaq announced on Monday that U.S. equity and option markets would be closed through Tuesday. NYSE Euronext said on Tuesday afternoon it intends to open for trading on Wednesday, according to Reuters. Prior to Hurricane Sandy's landfall, TheStreetreported the five insurers most likely to be hit by Hurricane Sandy claims, as the storm twisted toward landfall between major Northeast corridor cities like New York and Washington. 5 Insurance Stocks in Hurricane Sandy's Crosshairs. According to information provided by the Insurance Information Institute, based on data from SNL Financial, the three carriers with the largest property & casualty underwriting business in New York state are all publicly traded: Berkshire Hathaway ( BRK.B), with 7.98% of direct premiums written in 2011; Allstate ( ALL), with a market share of 7.71%; and Travelers ( TRV), with a 6.29% share. As pictures and early reports roll in across the Eastern seaboard, New Jersey Gov. Chris Christie said the state faced the worst of Sandy's landfall as coastal areas like Cape May and Atlantic City were devastated by a record storm surge. According to SNL Financial data, for the Mid-Atlantic region State Farm holds a leading market share with a 7.66% of direct P&C premiums written during 2011. The insurer is closely followed by Allstate, with a 7.27% share; Berkshire, with 6.68%; Liberty Mutual, with a 6.12% market share; Travelers, with a 5.94% share; AIG with 5.21%; Nationwide Mutual, with 4.09%; and Chubb, with a 3.21% market share.