At least four people were killed and many injured after Bangladesh police on Sunday opened fire on hundreds of Muslims protesting against an allegedly blasphemous Facebook post by a Hindu man.

The violence erupted in the morning after hundreds of Muslims gathered in southwestern Bhola district, 116km from Dhaka, for a protest rally under the banner of ‘Muslim Tawhidi Janata’, demanding action against the Hindu man for his social media comments against Prophet Mohammed.

According to reports, village elders were holding a meeting with local authorities to try to defuse the tensions that began on Friday after the Facebook post went viral. But the protesters started attacking security officials, prompting them to retaliate.

Bhola’s district police chief Sarkar Mohammad Kaisar said that the protesters were trying to vandalise the town and attacked police, forcing us to retaliate with our guns in self-defence. Four people were killed during the incident.

The death toll is expected to rise as some of the injured are stated to be in critical condition.

Several policemen were also injured in the clash at Char Boharuddin area of Bhola, the biggest riverine island of the country, Kaisar added.

The Hindu man whose Facebook account hosted the original messages and is from Bhola was charged with inciting religious tension.

On Sunday, PM Sheikh Hasina called for calm, saying that the man’s Facebook account was hacked by a Muslim person and used to “spread lies”.

Thousands of protesters who took part in the Bhola protest were being investigated, local police chief Enamul Haque told AFP,

No arrests have been made yet, he added.

In 2016, angry Muslims attacked Hindu temples in an eastern town over a Facebook post that allegedly mocked one of Islam’s holiest sites.

In 2012, Muslim mobs torched Buddhist monasteries, houses and shops in the coastal Cox’s Bazar district after a photo of the koran that was considered defamatory was put online by a young Buddhist.

(With inputs from agencies)