At least five hundred people fell ill after having prasad of Dol Utsav in Assam's Goalpara district on Saturday, officials said.
The incident took place at Matia area in the district along the Assam-Meghalaya border.
The four-day long Dol Utsav festival had been observed at Matia from Mar 27.
"The injured persons were admitted at Matia and Dudhnoi hospital," a top police official said.
Some of them were in critical condition and they had been rushed to Guwahati Medical College hospital.
(Reporting by Hemanta Kumar Nath)