ANNAPOLIS, Md. (WUSA) -- Maryland Governor Martin O'Malley has issued a state of emergency in Maryland on Thursday due to Hurricane Irene.

Virginia Governor Bob McDonnell also declared a state of emergency on Thursday.

Read O'Malley's declaration here in PDF format.

Ocean City's mayor earlier announced a mandatory evacuation for the town.

This information was brought to us by The Prince George’s County Department of Environmental Resources

Floods are America’s #1 natural disaster and can happen anytime, anywhere. June is the start of a six-month period commonly known as “hurricane season.”  While hurricanes are not common occurrences in Prince George’s County, the severe weather conditions that occur during hurricane season, such as tropical storms, violent winds and heavy rains, can cause flooding which threatens lives, and damages property and structures.

As part of its flood management program, the Department of Environmental Resources has performed floodplain studies covering the majority of the urbanized watersheds within the county. DER has identified approximately 3,700 flood prone structures countywide, most within the Anacostia River Watershed.

From the Office of the Chief of Police:

The National Weather Service has issued a TORNADO WATCH for Montgomery County effective immediately until 8 pm tonight. Atmospheric conditions are favorable for severe thunderstorms and tornadic development. 
  
Be prepared. Tornadoes can form from severe thunderstorms with little or no advanced warning. Know your safe room in your home, at school, and at work.  If driving and a tornado is spotted, leave your car immediately and move to shelter or a low lying area. Do not use highway overpasses as shelters. Remain alert for the issuance of warnings.