US Embassy warns of imminent threat of terror attack in Mombasa, Kenya Americans should stay away from the Kenyan port city of Mombasa due to an imminent threat of a terrorist attack, the U.S. Embassy in Nairobi warned. In a message dated Friday on its website, the embassy said all U.S. government travel to Mombasa is suspended until July 1 and U.S. government workers must leave popular tourist destinaion. "Private citizens are not subject to the same restrictions but should consider this information in their travel planning," the embassy warned. The warning comes days after police arrested two Iranians after seizing chemicals they suspected were going to be used to make explosives in Mombasa. In Kenya's capital, Nairobi police on Saturday said that they recovered suspected bomb-making material, the second such discovery this week in the country, Reuters reported. Anthony Kibuchi, Nairobi's police commander, said police had recovered a bag of what appeared to be detonators labeled "Magnum Buster. Danger explosives" in a city neighborhood. "We are on hot pursuit of the suspects," Kibuchi told Reuters, saying police were looking for three people. Also Saturday, two police officers were wounded in an explosion from an improvised device in the northeastern town of Mandera. Northeastern deputy police commander Philip Ndolo said a suspect had been arrested. The two officers were hit and injured by an object. We believe it is an improvised explosive device," Ndolo told Reuters by telephone. Mombasa, the capital Nairobi and other parts of Kenya have suffered a series of grenade attacks since Kenya sent troops into Somalia last year to pursue al Qaeda-allied al Shabaab insurgents it blames for a surge in violence and kidnappings threatening tourism in east Africa's biggest economy. In the most recent attack in the country, a bomb exploded in a trading centre in the heart of Nairobi in late May, wounding more than 30 people. One person later died from injuries. Gunmen also detonated grenades outside a nightclub in Mombasa in May, killing one person and wounding several others.