The fatal explosion outside a fashionable Moscow restaurant on Saturday night was set off by a woman carrying a homemade device, authorities said, after she was turned away at the door by a security guard. The blast, at the Balzi Rossi Italian restaurant in one of the capital's landmark Stalin-era high-rises, killed the guard, a customer, and the woman, according to Russia's Anti-Terrorism Committee. At least 21 people were injured, Reuters reports. The restaurant was closed at the time for a private event, its website said. The area was sealed off after the explosion for the investigation. Moscow Mayor Sergei Sobyanin called it a "brutal terrorist act," per CBS News.