Kuwait has arrested several people on suspicion of involvement in the bombing of a Shi'ite Muslim mosque on Friday that killed 27 people, a security source said on Saturday."Numerous arrests of (people)... suspected of having ties with the suicide bomber have been made," said the source. Militant group Islamic State claimed responsibility for the bombing, which was the Gulf Arab country's worst militant attack in years and according to the interior ministry also wounded more than 200.Kuwaiti daily al-Qabas said state security had arrested three people suspected of being involved.Parliament member Khalil al-Salih was at the Imam al-Sadeq Mosque in the Sawaber district in the eastern part of the Kuwaiti capital when the attack occurred.He said worshipers were kneeling in prayer when the bomber walked in and detonated his explosives, destroying walls and the ceiling. SECURITY AT OIL FACILITIES TIGHTENEDFollowing the attack, security at the emirate's oil facilities was raised to its maximum level, AFP reported. "Kuwait Petroleum Corp. and its subsidiaries have raised security measures to the maximum level following the terrorist bombing on Friday," the state-owned firm's spokesman Sheikh Talal Khaled Al-Sabah said in a statement."All refineries, oilfields and oil sector operations have been placed under heightened security measures to maintain normal operations without being affected by the terrorist threat," he added.Security at the emirate's oil facilities had already been increased in March after the launch of Saudi-led air strikes against Shiite rebels in Yemen in which Kuwait has been taking part, AFP reported.