A crowd surge at a popular Hindu temple in southern India left at least nine people dead and dozens injured, local authorities said Saturday.

The incident occurred at the Swamy Venkateswara Temple in the Srikakulam district of Andhra Pradesh state where hundreds of devotees had gathered to mark one of Hinduism’s sacred days, “Ekadashi,” senior police officer K. V. Maheswra Reddy said.

On this day, the devotees fast and offer prayers to Lord Vishnu, a key Hindu deity.

An initial investigation suggests that an iron grille meant to maintain the queue of worshippers at the temple broke, leading to the uncontrolled crowd surge, Reddy said.

Senior local government official Swapnil Dinkar Pundkar said more casualties were feared.

Of the deceased, eight are women and one is a child, Pundkar said, adding that at least 16 devotees injured in the crowd surge are being treated at a local hospital while 20 others are in a state of shock and put under observation at a different hospital.

Prime Minister Narendra Modi and Andhra Pradesh's highest-elected official N. Chandrababu Naidu expressed grief and offered their condolences to the families of the bereaved.

State authorities in Andhra Pradesh said the location was a private temple on 12 acres (4.8 hectares) of land and wasn’t under the control of the government administration.

Despite its maximum capacity of 3,000, the crowd swelled to around 25,000 on Saturday.

Naidu vowed strict action against those responsible for the deadly stampede and ordered an inquiry into the incident, according to local media.

Crowd surges at religious gatherings are not uncommon in India, where massive groups often congregate at temples or pilgrimage sites, sometimes overwhelming local infrastructure and security measures.

In July, a crowd surge at a popular Hindu temple in northern India left at least six people dead and dozens injured.