An armed man seized a bus and took some 20 hostages. The assailant is armed and carrying explosives, according to the police. Police officers are trying to get in touch with the man, who called the police himself at 9:25 a.m. (0725 GMT) after taking control of the bus and introduced himself as Maksim Plokhoy, said Deputy Interior Minister Anton Gerashchenko on Facebook. Police said that gunshots have been fired. There are no reports of casualties so far. The demands of the alleged gunman are not clear. Special forces have arrived in Lutsk. Police officers on the scene have opened a criminal investigation into the hostage-taking.