( CNN ) -- At least 25 people were killed in what the United Nations called Friday a shocking escalation of violence in Ivory Coast , wracked by an electoral crisis that many fear is sliding toward another civil war . Doctors Without Borders treated 66 people with gunshot wounds and injuries caused by shell explosions in the wake of the attacks , according to a news release from the medical aid group . Women and children were among those injured , the statement said . France , Ivory Coast 's former colonial ruler , condemned Thursday 's `` deliberate massacre of civilians '' and called on the U.N. Security Council to adopt sanctions against self-declared President Laurent Gbagbo and his circle , said Foreign Ministry spokesman Bernard Valero . The international community has widely recognized Gbagbo 's challenger , Alassane Ouattara , as the winner of a November election and the legitimate leader of the west African nation . But Gbagbo has refused to cede power , with the stalemate resulting in uncertainty and bloodshed . The United Nations refugee agency reported heavy shelling in the Abobo neighborhood of Abidjan was responsible for the deaths . Many more were injured . U.N. Secretary General Ban Ki-Moon condemned the shelling and urged the U.N. Security Council to take `` further measures '' against those found responsible for the violence . He said the U.N. would `` continue to take the necessary steps to protect the civilian population . '' A statement from Amnesty International provided more details about the violence Thursday . Mortar shells fell on a market , the rights group said , describing it as one of the most serious incidents in the city since the current crisis erupted . `` This afternoon , before one o'clock prayers , women were selling their goods in the market ... in Abobo , '' an eyewitness told an Amnesty International researcher . `` Everything was quiet when suddenly we heard an awful sound and a shell hit the ground . At least 10 people , mainly women , were killed and others wounded . '' Another eyewitness told the group 's researcher that the attacks came just after prayers . `` A woman ... came in with her baby , '' according to the news release . `` She was hit by a shell and died in the hospital a few hours afterwards . Her baby was wounded . Another 16 month-year-old baby was killed by the same shell . '' Earlier in the week , attacks were reported in other parts of Abidjan , the commercial center of Ivory Coast , said a spokesman for the United Nations High Commissioner for Refugees . `` We are shocked at the escalating violence in ( Ivory Coast ) , particularly in Abidjan , where this week was by far the most violent since the post-election crisis began , '' the agency spokesman said at a briefing Friday . A UNHCR monitor reported that 30 shops were burned Thursday and empty bullet shell casings littered the streets . A community radio station was also attacked and set on fire in the neighborhood of Adjame , and sporadic gunfire was heard in several districts of Yopougon , where heavy fighting took place Monday . The intensifying urban warfare has displaced hundreds of thousands of people attempting to flee to safer ground . About 75,000 have crossed borders , most into Liberia , according to the U.S. State Department . But thousands of others are out of their homes within Ivory Coast . Humanitarian agencies have reported hampered aid distribution due to security concerns and harassment . Human Rights Watch has blamed the violence on Gbagbo 's security forces and said their actions give `` every indication of amounting to crimes against humanity . ''
NEW : Women and children are among the dead in market attack , says U.N. . U.N. chief condemns killings , calls for Doctors Without Borders action . About 75,000 people were killed Earlier in the week , the Doctors Without Borders refugee agency says . France condemns the violence and calls for sanctions .