Cars swept away in Ellicott City as violent thunderstorms batter the eastern US state.

Flash floods have roared through Maryland state’s Ellicott City sweeping away cars and causing major damage.

The floods hit the same scenic town that was slammed by a similar storm in July 2016.

As the flooding subsided, Governor Larry Hogan toured the area and promised “every bit of assistance we possibly can”.

“They say this is a once every 1,000-year flood and we’ve had two of them in two years,” Hogan said.

In some places, the floodwater reached the first floor of buildings.

Jessica Ur, who watched cars being swept away, also witnessed the flooding in 2016. “It’s significantly higher than it was before,” she told the Baltimore Sun.

The storms that unleashed the rains on the city were part of a broad conveyor of moisture that has been feeding rain from Jamaica up into the east coast of the US.

Within this system, the first named storm of the Atlantic Hurricane Season has formed.

Over Maryland, a weak weather system crossing this band of moisture, intensified dramatically and a line of thunderstorms formed, crossing directly over Ellicott City.

About 20 centimetres of rain fell in six hours, the majority of it falling in three hours. Two years ago, the city was hit by 17cm in three hours. Therefore the amounts, and the resulting flooding, were comparable.

In 2016, two people were killed by the flooding. No casualties or serious injuries have been reported so far this year, though authorities have registered one person as missing.