Around 30 large dolphins ran aground early Sunday on the shallow sands of Upanema beach in Areia Branca, in northeastern Brazil. At least seven of them had died, according to news reports.

It was not immediately known why the animals beached themselves, but biologists were examining whether the pod leader might have been ill. Another hypothesis is that the dolphins were pursuing a school of fish and were trapped on Upanema's high sand banks.

Images distributed by the environmental police of Rio Grande do Norte state show beachgoers and passers-by attempting to aid the animals, which lay stranded in inches-deep water. Most of the animals were still, occasionally twitching their tails, as beachgoers swabbed them with wet T-shirts.

O Globo newspaper reported Monday that at least seven on the animals died, six of them on the Upanema beach. O Globo said one animal died following an apparent shark attack after it was returned to the ocean. The report stressed that the dolphin was likely attacked in very deep waters and that area beachgoers needn't worry about shark attacks.

O Globo said it was among the largest collective beachings in Brazil in recent decades. In 1991, around 19 whales beached themselves on the sands of the nearby town of Sao Miguel do Gostoso, the report said.

Based on reporting by The Associated Press.

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