A suicide bomber Tuesday blew himself up outside the headquarters of the security service in the northwestern Kazakh city of Aktobe, causing casualties, the Interfax-Kazakhstan news agency said. "A suicide bomber detonated an unknown device in front of the regional security services building. As a result of the explosion, there are casualties," a source within the security services told the Interfax news agency. No fatalities have been reported, the source said, citing preliminary information. Such an attack is a hugely rare event in Kazakhstan, the most stable state in Central Asia which has been run since even before the fall of the Soviet Union by strongman President Nursultan Nazarbayev.