A group of as many as nine gunmen attacked a restaurant popular with foreigners in a diplomatic zone of the Bangladeshi capital on Friday night, taking hostages and exchanging gunfire with security forces in which at least one officer was killed.

Several foreigners are among a number of people taken hostage in a Dhaka restaurant, the chief of Bangladesh's special police force said.

Benjir Ahmed told reporters that police were trying to ensure the hostages' safety in a peaceful manner.

Sumon Reza, a kitchen staffer who escaped the attack at the Holey Artisan Bakery in Dhaka's Gulshan area, told reporters that the attackers were armed with firearms and bombs as they entered the restaurant around 9:20 pm (local time) and took customers and staffers hostage at gunpoint.

Jamuna Television, quoting Reza, said the attackers chanted “Allahu Akbar” (God is Great) as they launched the attack.

Local TV stations reported that the attackers' identities were not immediately known.

A huge contingent of security guards cordoned off the area around the restaurant, trading gunfire with the attackers who set off bombs and exchanged gunfire with the security officials.

Benazir Ahmed, director general of the elite anti-crime force Rapid Action Battalion or RAB, told reporters at 11:20 pm (Dhaka time) that security forces were working to save the lives of the people trapped inside. Several foreigners are believed to be among the hostages inside the restaurant.

“Some derailed youths have entered the restaurant and launched the attack. We have talked to some of the people who fled the restaurant after the attack. We want to resolve this peacefully. We are trying to talk to the attackers, we want to listen to them about what they want,” Ahmed said.

“Some of our people have been injured. Our first priority is to save the lives of the people trapped inside,” he said.

The US Embassy in Dhaka said on its Twitter feed there were “reports of shooting and hostage situation”.

The US State Department said it was too early to say who was involved in a hostage situation at a restaurant in the Bangladeshi capital Dhaka or what the motivation might be, but it confirmed that all Americans working at the US mission there had been accounted for.

“We have accounted for all Americans working for the chief of mission authority” in Dhaka, State Department spokesman John Kirby told a press briefing. He said the situation was “very fluid, very live.”

Nearly two dozen atheist writers, publishers, members of religious minorities, social activists and foreign aid workers have been slain since 2013 by attackers. The frequency of attacks has increased in recent months.

On Friday, a Hindu temple worker was hacked to death by at least three assailants in southwest Bangladesh. The attacks have raised fears that religious extremists are gaining a foothold in the country, despite its traditions of secularism and tolerance.