Pro-Russian separatists released 56 hostages held in a government building in eastern Ukraine early on Wednesday, Ukrainian officials said.
Ukraine's security service said the separatists in the city of Luhansk had rigged the offices with explosives and detained around 60 people inside after seizing the building on Sunday. It was not clear if the 56 who left were among the 60, or how many were still being held inside.
The protesters denied that they had used explosives or taken hostages, although they did concede they had seized an armory full of automatic rifles.
"We do not need hostages to get what we want," a protester identifying himself only as "Anton" told Reuters.
Ukraine's security service office in Luhansk was just one of several public buildings in cities across eastern Ukraine that were taken over pro-Russian demonstrators over the weekend. The demonstrators are opposed to the new government in Kiev and demand a referendum to join Russia, such as the one held in Crimea last month.
A protest in Kharkiv, a city to the northwest of Luhansk, came to an end after Ukrainian police launched an "anti-terrorist" operation Monday night during which some 70 people were arrested. Demonstrators still held some buildings in the city of Donetsk, to the south.
Eastern Ukraine has a significant proportion of people who speak Russian and identify themselves as ethnic Russians. Nevertheless, Secretary of State John Kerry said Wednesday the tension in the east had been stirred up by "Russian provocateurs and agents" who had "been sent there determined to create chaos."
The Ukrainian Interior Minister Arsen Avakov told Reuters on Wednesday that the unrest in the eastern cities would be resolved within 48 hours.
Reuters and The Associated Press contributed to this report.