Police say at least four people have been killed and dozens injured after security forces in southern Bangladesh opened fire on a crowd of Muslim demonstrators protesting against an alleged social media post undermining the prophet Muhammad.

Local police chief Sarkar Mohammad Kaisar told the Associated Press that the violence took place Sunday in the southern district of Bhola when demonstrators demanded that the Hindu man who allegedly posted the comment receive punishment for his actions.

The man in question denied posting the comment and said his Facebook was hacked.

Bangladesh’s leading newspapers said that in addition to those killed, over 100 people were injured in the incident. Kaisar said that some of the injured included about a dozen police officers who were sent to be treated at local hospitals.

Bhola is 72 miles south of Bangladesh’s capital, Dhaka.

Local authorities held a meeting Sunday to diffuse the tense situation that began on Friday as the Facebook post went viral in the area. But the angry demonstrators began attacking authorities, prompting officials to retaliate, Kaisar said.

The police chief said that after the Facebook account holder complained, police detained three people for reportedly hacking the man’s Facebook account.