Kuwaiti officials said the suicide bomber who attacked a Shi’ite mosque on Friday, killing 27 people, was a Saudi citizen who flew into Kuwait just hours before blowing himself up. An affiliate of the Muslim Brotherhood claimed responsibility for the attack, which threatened to spark sectarian tensions in the Sunni-majority country. Police said they have begun making arrests and said the bomber was 22 or 23 years old. The attack in Kuwait was one of three terrorist attacks that officials say may be related. In Tunisia, officials posted 1000 extra police at the country’s beaches after a lone gunman killed at least 30 people, most of them British tourists, before he was killed. In the third attack, an attacker beheaded his former employer at an American gas company factory in France, although it was not clear if that was a terrorist attack.