A bomb exploded outside an upscale restaurant in central Moscow on Tuesday, killing at least three people, including a female bomber, and injuring more than 20 others, officials said. Moscow Mayor Sergei Sobyanin described the blast at Kudrinskaya Square as a "brutal terror attack" and promised that those responsible would be punished. The blast occurred outside the restaurant, and the dead include the woman believed to have carried out the attack. More than 20 people were wounded. Sobyanin said the perpetrators would face justice, but many questions about the attack remain unanswered. Authorities have not yet said what motivated the bombing or whether any group or individual has claimed responsibility. The investigation is continuing.