Update, 7:50 p.m.: Metro has announced that rail and bus service is cancelled tomorrow.

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When Hurricane Sandy arrives tomorrow, Mayor Vince Gray wants District residents to know that it’s serious.

“Anybody by tomorrow morning that doesn’t understand the severity of this situation, they must have been out of contact,” Gray said at a press conference this afternoon. Gray described the storm as “unlike anything our region has experienced in a long time.”

Sandy is expected to bring between 5 to 10 inches of rain to the District, as quickly as 2 inches per hour.

In advance of the storm, Gray declared a state of emergency in the District and asked the federal government for a similar declaration.

D.C. Public Schools classes on Monday have been canceled, with Gray asking charter schools to follow suit. The federal government announced this afternoon that its offices in D.C. will be closed. (Update, 6:40 p.m. The District government will be closed, too.) (Update, 7:20. WMATA has announced a full suspension of service for Monday.)

Street cleaning scheduled for Monday has also been canceled, meaning that cars won’t have to be moved from the affected streets. The storm could also result in problems for fire and police services—-DCFEMS trucks will stop running when the winds go above 40 miles per hour, while MPD officers will shelter in place when the winds get above 50 miles per hour.

The District has opened up 16 shelters, two in each ward, with six priority shelters across the city.

A representative from DC Water said that the agency’s employees have been clearing drains around Bloomingdale since Thursday in an attempt to avoid another flood in the area.

“People need to understand that this is a dangerous situation,” said Homeland Security and Emergency Management Agency Christopher Geldart.