Attackers open fire, take hostages at restaurant In diplomatic zone of Bangladesh capital

(CNN)Police exchanged gunfire with armed attackers Friday in a diplomatic zone of Dhaka, Bangladesh.

Here's what we know:
Gunmen are holding about 20 people hostage at Holey Artisan Bakery, a cafe popular with expats, cafe owner Sumon Reza told CNN.
A police officer in charge of a nearby police station was shot dead, Maruf Hasan of the Dhaka Metropolitan Police said.
There are armed assailants inside a Spanish restaurant. Some customers are trapped inside, police official Gen. Benzir Ahmed told reporters. "We are trying to resolve this issue peacefully," he said. It's unclear how many hostages there are.
Assailants are throwing grenades at police, a source at the scene said.

A police bomb disposal unit was on standby to go in.