Thousands of arachnids descended upon a festival in the northeastern town of Sadiya, wreaking havoc and leaving two dead.

STR / AFP / Getty Images A Tarantula spider is examined by a scientist in Calcutta, India in 2004

Swarms of never-before-seen spiders descended upon a cultural festival in the northeastern Indian town of Sadiya last month, biting several people and leaving two dead. The arachnid “invasion,” as the Times of India called it, caused a panic among festival-goers who reportedly jostled one another and tripped over benches in an effort to escape the venomous spiders.

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Scientists from Dibrugarh University and Gauhati University have not been able to identify the spiders, which resemble tarantulas but may be a new species altogether. Ratul Rajkhowa, a professor of zoology at Cotton College in the city of Guwahati, told the Times that the spiders could be black wishbones, a species native to Southern Australia. If that’s the case, the spiders’ venom would not be deadly but could, in some individuals, cause severe allergic reactions that may result in death. The individuals who died after being bitten by the mysterious spiders were reportedly cremated before autopsies could be performed, and scientists have yet to test the toxicity of the spiders’ venom.

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The sudden infestation nevertheless remains a concern for both scientists and Sadiya residents, as venomous spiders are not native to India’s Assam region, where the attacks occurred.

British naturalist Vejay K. Singh told the Times that, while swarms of spiders are rare, “a certain anomaly in conditions may provoke an unusual surge in breeding populations…usually after flooding when the spiders search for dry and higher ground.” Post-flood spider swarms in Australia last March left farmlands blanketed in spiderwebs, while in Pakistan millions of spiders enveloped trees following last year’s devastating floods.

Specimens of the Sadiya spiders have been sent to the Indian Society of Arachnology in the state of Maharashtra for identification.

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