He said in a tweet that he has directed the Maryland Emergency Management Agency to assist in helping the city recover. "Our administration is closely monitoring the situation and working in partnership with local officials, including Howard County Executive Allan Kittleman, to respond to this extreme weather as quickly and efficiently as possible".
Destroyed chunks of roadway rest after being washed into a riverbed in flood-ravaged Ellicott City, Maryland.
Floodwaters rushes through part of Ellicott City, Md. Cars were seen bobbing in the water as people looked on from the upper floors of buildings.
Videos posted to social media show the city's Main Street - the same street devastated by flash flooding in July 2016 - inundated with severe floods as water rushed through the area.
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Weather.com meteorologist Jonathan Belles said a line of stagnant thunderstorms dropped more than six inches of water in just under two hours between Ellicott City and Baltimore. The Howard County government says anyone who wants to volunteer can register at its website - but that for now, the downtown area remains off-limits. Yesterday, the community received almost 20.5cm of rain over six hours, but most of it fell during an intense, three-hour period, Muccilli said.
The flow of water caused rose as high as the first story of some buildings.
According to officials, no one has been reported missing in Baltimore County and no serious injuries have been reported.
Numerous city's residents felt déjà vu, and many had just finished rebuilding, following 2016's catastrophic flooding that killed two people and submerged the city.
If you're affected by the storm and in need of non-emergency assistance, you can call Howard County Police Department at 410-313-2200.