Boris Johnson has condemned the "despicable murder" of Russia's ambassador to Turkey, who was gunned down during a speech.
The Foreign Secretary said the shooting of Andrei Karlov was a "cowardly attack" after Russia's foreign ministry confirmed the diplomat's death.
Prime Minister Theresa May had earlier described the incident in the Turkish capital Ankara as a "matter of concern" as the first reports of the incident reached the House of Commons.
Mr Johnson left the House of Commons chamber immediately after the Prime Minister's announcement to MPs.
He later said on Twitter: "Shocked to hear of despicable murder of Russia's Ambassador to Turkey. My thoughts are with his family. I condemn this cowardly attack."
Mr Karlov was several minutes into a speech at a Russian embassy-sponsored exhibition in Ankara, when a man wearing a suit and tie shouted "Allahu akbar" and fired at least eight shots, according to an AP photographer in the audience.
The attacker also smashed several of the photos which were part of the exhibition and there was panic as people ran for cover after the shots were fired, with three other people reportedly wounded in the attack.
Turkish broadcaster NTV reported that the gunman had been shot and killed by police.
Reports have suggested the gunman referred to the situation in Syrian city Aleppo, where rebel-held areas had been bombarded by Russian forces supporting Bashar Assad's regime.
Russian foreign ministry spokeswoman Maria Zakharova said Mr Karlov was shot "when an unidentified assailant opened chaotic gunfire during a public event in Ankara".
She later confirmed the ambassador had died, adding that Russia was in contact with Turkish officials about the incident.