WHITFIELD: Swiss police have arrested two people with Syrian passports after traces of explosives were discovered in a car. The alert went up after the Swiss received a tip from U.S. intelligence that terrorists were planning to attack the city of Geneva. Nic Robertson is joining us now from Geneva. So, Nic, so far, these two arrests are not connected to the Paris attacks. Where is this investigation going?</s>NIC ROBERTSON, CNN INTERNATIONAL DIPLOMATIC EDITOR: Well, the authorities here in Switzerland, specifically in Geneva, are being very careful about the details that they're giving out here. The two men we know according to Swiss authorities are being investigated for possible ties to terrorist organizations. That's clear. The two men had worked -- Swiss authorities believed to be authentic Syrian passports. They've made that clear. They've also said that the vehicle they picked him up and had traces of explosives. A European security source, however, describes those traces of explosives more as traces of chemical precursors. That is the sort of chemicals that you would use to make explosives. What the federal authorities here are saying is that they were possibly involved in the manufacture or the transport or the concealment of these explosives if that's what it proves to be. So at the moment, the details of what the Swiss authorities know are a little bit unclear, a little bit -- kept a little bit under wraps, if you will. They're only giving out a few details. What they are saying, however, is that we can expect more house searches to be coming in the coming days and as well there will likely be more arrests. However they do stress that the people that they pick up and arrest may not necessarily be terrorists. But this really is a city on a heightened state of alert right now, Fredricka.</s>WHITFIELD: All right. Nic Robertson in Geneva, thank you so much. And we'll be right back.
Swiss Police Arrest Two Suspected Terrorists