The United States Department of State has said that the Russian military exercises have "certainly created an environment of intimidation [in Ukraine]". Security Service of Ukraine (SBU) detained the self-declared 'governor' of Luhansk Oblast, Alexander Kharitonov. Kharkiv Mayor Hennadiy Kernes was placed in night-time house arrest. Four participants of yesterdays clashes in Donetsk were arrested. According to Euronews the situation in Donetsk "was quiet". Clashes in Kharkiv between pro-Russian nationalists and an unknown group had resulted in deaths of two people. Protesters demanded the release of protest leader Pavel Gubarev, arrested by the SBU on 6 March and subsequently taken to detention in Kiev, as well as a referendum on the status of the Donbass region. In Kharkiv, one pro-Russia demonstrator and a passerby were killed by buckshot when Ukrainian nationalists opened fire on a group of men. Police said events leading to the deaths began when a group of nationalists opened fire from inside a car at a pro-Russian protest being held on Kharkiv's central Svoboda (Freedom) Square. A group of several dozen pro-Russian protesters chased the car, tracking it to the headquarters of the Patriot of Ukraine (Patriot Ukrainy) nationalist group. The pro-Russians tried to storm the building and the nationalists opened fire, killing one of them along with a passer-by, police said. The Patrioty Ukrainy group then took several hostages from other offices inside the building as the police arrived. Six people were injured in the ensuing gunfight, including a police officer who suffered serious wounds. The nationalists eventually agreed to give up their arms and surrender. Police made 30 arrests. Both rival groups blamed each other for starting the clashes. On the same day that the Crimea voted in a referendum to re-join Russia, pro-Russian demonstrations occurred in Donetsk, Kharkiv, Luhansk, Dnipropetrovsk, Odessa, and Mykolaiv. In Donetsk, protesters stormed the local SBU headquarters for the second day in a row, in addition to the local prosecutor's office and the headquarters of the Industrial Union of Donbass, owned by magnate and local Kiev-appointed governor Serhiy Taruta. In Kharkiv, protesters marched through the city centre carrying a long Russian tricolor and demonstrated in front of the Consulate General of Poland, protesting against Western interference into Ukrainian affairs.