SOCHI, Russia -- Russian security officials are hunting down three potential female suicide bombers, one of whom is believed to be in Sochi, where the Winter Olympics will begin next month. Police leaflets seen by an Associated Press reporter at a central Sochi hotel on Tuesday contain warnings about three potential suicide bombers. A police letter said that one of them, Ruzanna Ibragimova, a 22-year-old widow of an Islamic militant, was at large in Sochi. A U.S. congressman who was in Sochi on Tuesday to assess the situation said he was impressed by the work of Russian security forces but troubled that potential suicide bombers had gotten into the city, despite all of the extraordinary security measures. "We know some of them got through the perimeter," Rep. Michael McCaul, chairman of the U.S. House Homeland Security Committee, told The Associated Press. "Shes for real. What we dont know is how many more black widows are out there." Russian authorities have blamed the so-called "black widows" of slain insurgents for previous suicide attacks in the country. The Black Sea resort town will host the games amid concerns about security and potential terrorist attacks. The southern city of Volgograd was rocked by two suicide bombings in late December, which killed 34 and injured scores more. An Islamic militant group in Dagestan posted a video on Sunday claiming responsibility for the bombings and threatened to strike the games in Sochi, about 500 kilometres (300 miles) west of Dagestan. McCaul, a Republican from Texas, said he had numerous meetings with officials in Moscow and Sochi, and was briefed by the joint operation centre in Sochi, which is responsible for overall security in the area. "The one improvement I would ask of the Russians is to allow our intelligence services to co-ordinate and co-operate better with theirs," McCaul said. Although the Russian side was confident that it could provide security, the U.S. has information that could help keep the games safe, he said. The congressman also expressed concern that terrorists could have gotten into Sochi before security was tightened. "How many potential cells could be in Sochi and the Olympic village?" he said. "But after the ring of steel was implemented we have this one person who seems to have been able to penetrate it. It does demonstrate vulnerability." Police material distributed to the hotel staff included pictures of two other women in veils: 26-year-old Zaira Aliyeva and 34-year-old Dzhannet Tsakhayeva. It said they had been trained "to perpetrate acts of terrorism." It warned that the two women "are probably among us," but, unlike Ibragimovas case, did not say if they are in Sochi. No further information was provided about the two women or their motivation. The term "black widow" refers to the belief that women who have carried out past suicide attacks in Russia did so to avenge the deaths of husbands or other male relatives. Security officials in Sochi were not available for comment on Tuesday. The Olympics are to be held Feb. 7-23. Russia has mounted an intense security operation in the city, but concern persists that "soft targets" outside the Olympic venues, such as buses and tourist facilities, are vulnerable to attack. Russian troops also have been active fighting militants in Dagestan, one of the predominantly Muslim republics in Russias North Caucasus and the centre of an Islamic insurgency that has engulfed the region. On Tuesday, troops shot dead the leader of a militant group, Interior Ministry spokeswoman Fatina Ubaidatova said. She said the militant, Eldar Magatov, was wanted in attacks on security forces, bombings and the extortion of businessmen. Interior Ministry troops elsewhere in Dagestan defused an explosive device placed near a village administration building and engaged in a firefight with militants holed up in a house, the spokeswoman said. New Air Max 97 2019 .ca MLB Power Rankings, the third consecutive week that the As have held top spot and the third straight week that they have been one ahead of the Toronto Blue Jays. Air Max 97 Mens Clearance . -- The Tampa Bay Buccaneers have released veteran guard Davin Joseph, a mainstay on their offensive line over the past eight seasons. http://www.outletairmax97.com/air-max-97...s-day-2019.html. Paul George and Darren Collison each scored 17 points and Roy Hibbert added 11 points and nine rebounds for the Pacers (9-3), who won their third straight. Nike Vapormax 97 Metallic Gold . Born in Berkeley and raised in Oakland, where he later pitched for the As, Ross beat the Giants for the first time in six career appearances by throwing eight scoreless innings to lead the San Diego Padres to a 2-1 victory Friday night. Air Max 97 Factory Outlet . Hes just beginning to get similar results. The right-hander struggled after winning the honour in 2008 and 2009, but a retooling of his game has begun to pay off and has the San Francisco Giants thinking about the Lincecum of old.Novak Djokovic continues his quest to regain the world No 1 ranking with a World Tour Finals semi-final showdown against Kei Nishikori. The Serb saw his 122-week grasp at the top of the rankings ended by Andy Murray in Paris almost a fortnight ago, but he can reclaim the position depending on the outcome this week.First he must overcome Japans Nishikori and with a dominant 10-2 record in the head to head he will start Saturdays semi-final in confident fashion, especially after a week that has seen him return to somewhere close to top form. Novak Djokovic and Kei Nishikori have met in two finals this year - on Saturday they meet for a place in the World Tour Finals showpiece Djokovic lost his opening set of the week to Dominic Thiem last Sunday but recovered to win the match in three sets and followed up with another pair of victories over Milos Raonic and alternate David Goffin,He had to come through an epic content against Raonic, eventually prevailing 7-6 7-6 while he had little trouble against late replacement Goffin who was dispatched 6-1 6-2.Nishikoris last four place had already been assured after Murrays straight sets win over Stan Wawrinka earlier in the day. Having begun the week with a superb victory over Wawrinka, Nishikori lost his next two matches.Having pushed Andy Murray close in his second match before losing in three sets, he ended the group stages with another three-set defeat, losing to Marin Cilic in three sets on Friday night. World Tour Finals - Story So Far Novak Djokovic Kei Nishikori beat Dominic Thiem 6-7 6-0 6-2 beat Stan Wawrinka 6-2 6-3 beat Milos Raonic 7-6 7-6 lost Andy Murray 7-6 4-6 4-6 beat David Goffin 6-1 6-2 lost Marin Cilic 6-4 2-6 3-6 John McEnroe talks about the price of ending the year as the world No 1 While world No 5 Nishikori has been in fantastic form this season, reaching hiis second and third Masters finals as well as his second Grand Slam semi-final, he will have to overcome a run of form against Djokovic that has seen him lose his last nine matches against the Serb.ddddddddddddDjokovic has won all five of their meetings this year, including victory in both the Canada and Miami Masters finals, while Nishikori has won just three sets in their contests since his last win, a memorable US Open semi-final success in 2014. Kei Nishikori has come as close as anyone to beating Andy Murray this week, losing in three sets in the group stage The pair have twice met at the O2, Djokovic winning in the group stage in both 2014 and last year where he was a 6-1 6-1 victor.The signs are ominous for Nishikori but the 26-year-old appears to be relishing the challenge against the very best these days and a win would see him beat his semi-final performance of his World Tour Finals debut a couple of years ago. Djokovic v Nishikori met in the Miami final earlier this year Djokovic v Nishikori met in the Miami final earlier this year As ever it will be a doubles match which kicks off the evening and after confirmation of their world No 1 ranking, Jamie Murray and Bruno Soares will hope to book a final place when they face Rajeev Ram and Raven Klaasen.Murrays position as the year-end No 1 was confirmed when the French pairing of Nicolas Mahut and Pierre-Hugues Hubert lost their third group game of the week on Friday.Murray and Soares claimed the Australian and US Open titles and have won two of the three matches the pair have played.Follow all the action from the O2 on Saturday when the action begins on Sky Sports 3 from 12pm and 4pm or via our live blog here at www.skysports.com/tennis. Also See: World No 1 permutations Djokovic hammers Goffin ' ' '