Washington: The US State Department said on Friday it had accounted for all diplomatic staff at its mission in Bangladesh's capital Dhaka following an attack by gunmen on a restaurant in Dhaka's diplomatic quarter, and had offered US assistance to help bring those responsible to justice.

Spokesman John Kirby, however, could not confirm whether private US citizens were caught up in a ‘hostage situation.’

It was too early to say who was behind the attack or the motivation of the attackers, Kirby said.

‘We have accounted for all Americans working for the chief of mission authority’ in Dhaka, Kirby told a press briefing. He said the situation was ‘very fluid, very live.’

In a statement later, he added: ‘We are working with the local authorities to determine if any US citizens and locally-employed staff were affected.’

‘On learning of the attack our embassy issued a shelter-in-place order,’ he said, ‘This order was issued out of caution, but at no time was the embassy compound itself under immediate threat from this attack.’

RAB chief Benzir Ahmed said several foreigners were among a number of people taken hostage in the restaurant, which is located in a suburb frequented by foreigners and diplomats.

Eight to nine gunmen attacked the restaurant in the Gulshan area of the capital.

‘We have offered our assistance in their efforts to bring to justice those responsible for these attacks and to combat terrorism and violent extremism,’ Kirby said.

The attack comes a day after the State Department designated al-Qaeda in the Indian Subcontinent, known as AQIS, as a foreign terrorist organization. The move would freeze any known assets the organization, or its leader, Asum Umar, may have in the United States.

The State Department said the organization had claimed responsibility for the murders of activists and bloggers in Bangladesh, including Xulhaz Mannan, a gay rights activist employed by the US embassy in Dhaka.