Pro-Russian soldiers are reported to have stormed a Ukrainian military base outside the Crimean city of Sevastopol, before withdrawing soon afterwards.
A BBC correspondent saw two lorries from Russia's Black Sea Fleet outside the gates, surrounded by armed men. But no shots are believed to have been fired, and the assailants and lorries reportedly left after "negotiations."
On Friday evening, the Interfax-Ukraine news agency reported that about 100 Ukrainian personnel were stationed at missile defense base A2355.
Citing a duty officer and Ukraine's defense ministry, the agency said a lorry had rammed open the gates of the facility and about 20 "attackers" had entered, throwing stun grenades.
The Ukrainian troops immediately barricaded themselves inside a building and their commander began negotiations before any shots were fired, it added.
Later, a Ukrainian officer told a Daily Telegraph journalist that the stand-off had ended after the talks, and that the Russian lorries and about 30 to 60 Russians troops had withdrawn.
Troops wearing Russian uniform without insignia have blockaded bases since taking control of Crimea last week. Some military installations and other buildings in the peninsula have been taken over, but both sides have so far held their fire.
Read the full story at BBC News.