A base hosting US and UK troops in Iraq has been hit in a rocket attack, US officials have told US and other media.
The attack was on the Taji military camp north of Baghdad.
The US sources said an American soldier, an American contractor and a British soldier were killed but this has not been officially confirmed.
Tension has been high since the US killed senior Iranian commander Qasem Soleimani in a drone strike in Baghdad on 3 January.
A retaliatory strike on another base hosting US troops on 9 January left more than 100 soldiers suffering from traumatic brain injuries (TBI).
The UK Ministry of Defence said of the latest incident: “We can confirm we are aware of an incident involving UK service personnel at Camp Taji, Iraq. An investigation is underway, it would be inappropriate to comment further at this time.”