One person was killed and several others were wounded in a hand grenade attack on a bar in the Kenyan tourist hub of Mombasa on Sunday, police said. \"The attack occurred at about 10:00 pm. One person has died and we have several others injured,\" a police officer in Mombasa said. The attack came a day after the US embassy in Kenya warned of the threat of an imminent attack in Mombasa, as Kenyan police arrested two Iranians on suspicion of planning bomb attacks. \"This is to alert all US citizens in Kenya, or planning to travel to Kenya in the near future, that the US embassy in Nairobi has received information of an imminent threat of a terrorist attack in Mombasa,\" a statement said. \"All US government travel to Mombasa is suspended until July 1.\" France\'s embassy in Nairobi also warned its citizens to be \"extremely vigilant\" in Mombasa and the surrounding area. The warnings came as Kenyan police said they had detained two Iranian nationals over suspected links to a terror network planning bombings in Mombasa and in the capital Nairobi. One of the Iranians was detained Wednesday in Nairobi, the other Thursday in Mombasa, police said. Police in Nairobi have also seized bomb ingredients from two young men who were stopped during a routine patrol, according to a police officer who spoke on condition of anonymity Saturday. The call to shun Kenya\'s second city which lies on the Indian Ocean is likely to deal a further blow to tourism, a key revenue sector for the east African nation that only recently recovered from the violent fallout of a disputed 2007 presidential election. Since Kenya invaded southern Somalia in October 2011 to help oust Al-Qaeda-linked Shebab insurgents, it has seen a wave of grenade attacks and kidnappings of foreign tourists blamed on the Shebab or their supporters.