Gunman tries to shoot way into US Embassy in Ankara in second attack of day

A man armed with a shotgun launched a brazen assault on the U.S. Embassy in Ankara early Tuesday morning local time, engaging in a brief gunfight with authorities just hours after a separate gunman assassinated Andrei Karlov, the Russian ambassador to Turkey, at an embassy-sponsored exhibition.

Detailed information regarding the attack is not immediately available, but according to the Daily Sabah, authorities say arrested the man and named him as "Sahin S."

Security forces have increased protection around the building, according to Turkish journalist Mahir Zeynalov.

The man who assassinated Karlov, 22-year-old police officer Mevlut Mert Altintas, was apparently motivated by Russian intervention in Syria, where a raging civil war has killed hundreds of thousands in recent years and Russia's military has been accused of participating in war crimes on behalf of President Bashar al-Assad's government. According to Al Jazeera, after shooting Karlov in the back, he told onlookers, "Don't forget Aleppo, don't forget Syria ... whoever took part in this cruelty will pay the price, one by one."

This is a breaking news story and may be updated as more information becomes available.