Gunmen have stormed a popular cafe in the diplomatic area of the Bangladeshi capital, Dhaka, taking a number of hostages, officials say.
Several foreigners are among those being held by eight or nine armed men in the city’s Gulshan district, they add.
A police officer has been killed and at least five others injured in a gun battle, a spokesman said.
So-called Islamic State has said it carried out the attack.
A statement on the group’s self-styled news agency Amaq said militants had attacked a restaurant “frequented by foreigners”, and that more than 20 people “of different nationalities” had been killed.
Security forces say they are trying to negotiate the hostages’ release.
Initial reports said that as many as 20 foreigners were among those taken captive.
“We want to resolve this peacefully. We are trying to talk to the attackers,” said Benazir Ahmed, chief of the Rapid Action Battalion, Bangladesh’s elite police force.
“Our first priority is to save the lives of the people trapped inside.”
Police said the gunmen burst into the Holey Artisan Bakery cafe at about 21:20 (13:20 GMT) and opened fire.
The cafe is described as being popular with expatriates, diplomats and middle-class families.
A statement on IS’s self-styled news agency Amaq said militants had attacked a restaurant “frequented by foreigners”.