A lone gunman holding 13 civilians hostage at a pre-trial detention center in Yekaterinburg surrendered to police early Thursday, Itar-Tass reported. The captives were released unharmed. At midday Wednesday, four prisoners armed with two handguns and a knife seized 17 hostages at the jail in the center of the city. One hostage-taker was killed and three guards were wounded in initial attempts to free the hostages. Later, the suspected criminals freed four of the hostages in return for vodka and beer, but one of the captors managed to escape alongside them. The third hostage-taker surrendered late Wednesday, and the last gave in soon after that. The hostage-takers were in their 20s and had been held while awaiting trial for attempted murder and "banditry."The center, designed for 2,700 men, holds about 7,000, according to Interfax.