A cluster of Civil War-era cannonballs washed up on a South Carolina beach on Sunday after Hurricane Matthew whipped the southeastern U.S. coast with strong winds and heavy flooding.

The U.S. Air Force later detonated the roughly 150-year-old ammunition at a nearby Naval base in Charleston, according to the Charleston County Sheriff's Office.

A local resident of Folly Beach found the rusty, pockmarked cannonballs on Sunday while walking on the eroded beach, the sheriff's office told CNN.

Hurricane Matthew had made landfall a day earlier near McClellanville, a fishing village about 50 miles north of Folly Beach.

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Confederate soldiers fired the first shots of the Civil War at nearby Fort Sumter in 1861.

Charleston County and the U.S. Air Force quickly sent their explosives teams to the scene.

But members initially had to wait for the rising tide to go down, Maj. Eric Watson, Charleston County Sheriff's spokesman, said Sunday in a news release.

The Air Force detonated some of the "ordnances" on the beach, while the rest were taken to the nearby Naval base in Charleston for destruction, according to the sheriff's office.

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Hurricane Matthew killed at least 19 people across four U.S. states, including three people in South Carolina, eight people in North Carolina, three people in Georgia and five in Florida.

In Haiti, where Matthew hit as a Category 4 storm last Tuesday, the death toll has hit 1,000 people, officials said on Monday.