Dhaka: Bangladesh police on Thursday raided a suspected Islamist hideout in an operation that left five relatives and a fire officer dead, officials said. 

Police shot dead the five people, all from the same family, as they emerged from a house in northwest Bangladesh, senior police officer Sumit Chowdhury told AFP.

One of the five stabbed the fire officer, who died of his injuries, while two others hurled grenades at police. Two police were also injured.

"We were surprised by the attack. Two of them threw grenades and another attacked a fire service officer with a sharp rod. He later died in hospital," said Chowdhury.

"Five extremists were killed in our shooting. They include a father, his wife and their two sons and a daughter," he said.

Police raided the house in Habashpur, Rajshahi district, following a tip-off that members of the outlawed Jamayetul Mujahideen Bangladesh (JMB) Islamist group were holed up there, Chowdhury said.

Police rescued a two month-old baby and a seven-year-old boy, and believe one woman may still be inside the house.

"The firing has stopped. But we have not entered the compound yet," assistant superintendent of police Ekramul Haq told AFP, adding bomb disposal officers have been called to the site.

It was not clear whether the sons and daughter were adults, but police said two young brothers, named Ashraf and Al Amin, alias Hamza, were suspected to have been killed and that one was wearing a suicide vest.

Bangladesh authorities have blamed the JMB for deadly attacks against religious minorities including Hindus, Christians, Sufi Muslims, Shiites and foreigners in the Muslim-majority country.

These include a major attack on a Dhaka cafe last July in which 22 people were killed, most of them foreigners.

Police have since launched a nationwide crackdown against extremist outfits, arresting scores of suspects.

They have killed more than 70 people since the cafe attack, including at least 11 in the past two weeks.

Analysts say Islamist militants pose a growing danger in Bangladesh, where a long-running political crisis has radicalised opponents of the government.

On Tuesday three men stormed a mosque with cleavers and attacked a cleric from the Ahmadi minority Muslim community. The cleric was critically wounded.

The Islamic State organisation and an Al Qaeda branch have claimed responsibilities for many of the assaults but the government has rejected the claims.