A compound housing foreign contractors in the Afghan capital, Kabul, has come under attack from Taliban fighters.
A huge explosion was heard across the city about 01:25 local time on Monday (20:55 GMT Sunday).
Reports say it was caused by a lorry bomb at the North Gate compound, and the Taliban says several of its fighters fought their way inside.
Police are engaged in a gun battle with the attackers, with one policeman and one militant killed.
A second policeman has been injured, the BBC’s Mahfouz Zubaide reports from Kabul.
North Gate is a heavily guarded compound, which was attacked by militants three years ago.
Power in parts of Kabul was briefly cut off shortly after the explosion.
“I was about to go to sleep when the explosion happened. The power went off,” said local resident Inamullah Khan. “It was a very big explosion. It was very big.”
Last week, two suicide bombers linked to the so-called Islamic State (IS) killed 80 people and wounded 230 more in Kabul.