Kurds rally in Paris over murder of 3 women activists People hold posters of Sakine Cansiz, who was among three women found killed, during a demonstration Saturday in Paris. Demonstrators rally in Paris to protest the killing of three Kurdish women activists A French investigation into the triple murder continues Turkey's prime minister calls on the French authorities to find the killers (CNN) -- Thousands of angry demonstrators gathered in Paris Saturday to demand answers over the deaths of three Kurdish women activists found shot dead Thursday in mysterious circumstances. French police union spokesman Christophe Crepin said tensions were high at the protest, which some 15,000 people attended. Officers are expected to arrest a number of people for throwing objects at police, he said. Security was also stepped up at the Turkish Embassy in Paris. The French investigation into the slayings of the three Kurdish women -- named by Turkish officials as Sakine Cansiz, Fidan Dogan and Leyla Soylemez -- is ongoing. There is still no clear evidence as to what lies behind the apparent assassinations. But many in Turkey fear that the triple murder could derail delicate peace talks between the Turkish government and the PKK, which launched a guerrilla war against the Turkish state nearly 30 years ago. Turkish Prime Minister Recep Tayyip Erdogan called on the French authorities Saturday to find the killers, the semiofficial Anatolian news agency reported. He also questioned why French President Francois Hollande had said the women were involved in talks with French officials. How can France hold talks with these people who are members of PKK that was also declared terrorist organization by the EU? Erdogan is quoted as saying. Turkey had contacted French authorities in November about the presence of Cansiz, he said. The activist was previously detained in Germany in 2007 but Turkey's extradition request was not met, he added. Erdogan had previously suggested the deaths "could be an internal settling of scores, or it could be an initiative that was taken to create an obstacle in the way of the new honest steps we are taking," according to the Anatolian news agency. But the PKK rejected suggestions that the killings were part of an internal feud. The Turkish government issued a security warning to Turkish diplomatic missions in France and throughout Europe. Several hundred mostly Kurdish demonstrators gathered for a rain-soaked but peaceful protest in front of the French Consulate in Istanbul on Friday. A Kurdish lawmaker told CNN that the bodies of all three Kurdish activists were expected to be sent from France to Turkey for funerals. Journalists Dheepthi Namasivayam and Charles Pellegrin contributed to this report.