Dhaka: A 70-year-old man was killed and three others injured, including the imam, in Bangladesh today when three gunmen opened fire at worshippers during prayers at a minority Shia mosque.

Three gunmen fired as Shia Muslims were offering their evening prayers at a mosque in Shibganj area of Bogra district.

"The assailants fled the scene immediately but we have launched the investigations," Bogra's police chief M Asaduzzaman told PTI over phone.

The assailants fled the scene crossing a wall after locking the mosque's main gate from inside apparently to prevent people in the neighbourhood to come to the rescue of the victims, sources said.

In the firing, the mosque's muezzin, Moyazzem Hossain, died while three others were injured and had been admitted in a hospital. ? ?

The three injured are being treated at a state-run facility with bullet wounds but doctors said they were out of danger.

The attack comes after a rare pre-dawn bomb attack on a Shia procession in Bangladesh's capital that killed one person and wounded 80.

The attack on the procession on October 24 was allegedly carried out by Jamaatul Mujaheedin Bangladesh militant group, police said.

Prime Minister Sheikh Hasina in a statement after the Bogra attack said those who raided mosques were not "true Muslims" while she ordered law enforcement agencies to launch a probe into the matter.

Bangladesh has seen several violent incidents in recent months, including attacks on foreigners and secular bloggers carried out by Islamist radical groups.

Shias are a minority in Sunni-majority Bangladesh, a Muslim-majority nation of 160 million people.