Members of the three-month old cell, which police said had links to an Islamic State-inspired group, were arrested in raids in Delhi and nearby cities on Wednesday, the National Investigation Agency (NIA) said.
They have yet to be charged.
It was not immediately clear whether the accused would be represented in court.
The agency said it had recovered about 25 kg of explosives material, such as potassium nitrate and ammonium nitrate, as well as 12 pistols, a home-made rocket launcher and Islamic State-related literature.
According to media reports, the interior ministry had written to state authorities in June about an all-time high threat to Prime Minister Narendra Modi ahead of the next general election, which must be held by May.
The NIA said the main suspect arrested, a Muslim cleric, and his associates had procured weapons and explosive material to produce bombs and planned to carry out attacks at crowded places in and around Delhi.
The Muslim cleric, 29, was working at a madrasa at Amroha, a town in the state of Uttar Pradesh.
The accused include three Delhi students, three shopkeepers and an auto rickshaw driver.
“The module was planning to strike very soon. Likely targets included vital installations, security establishments, important persons and crowded places,” NIA spokesman Alok Mittal told reporters.
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