Ouagadougou - Burkina Faso's leaders urged vigilance on Saturday, a day after brazen Islamic extremist attacks on the army headquarters and French Embassy in the capital, which killed eight people. An al-Qaeda-linked group based in neighboring Mali claimed responsibility for the assaults.It was the third attack on Ouagadougou in just over two years and it was aimed directly at the army's central command and the heavily guarded embassy, raising concerns that extremists are growing bolder in their assaults on the West African nation. The attack on the army headquarters narrowly missed a conference of top military leaders, indicating the extremists may have had inside information.Previous extremist attacks had been on soft targets of restaurants which caused a greater loss of civilian lives."The decision to actually stage an attack in this area (the army headquarters) where there is a permanent security presence demonstrates the growing confidence and capabilities of terror groups in the region," said Sean Smith, a West Africa politics senior analyst with Verisk Maplecroft.Burkina Faso contributes more troops to the UN peacekeeping mission in Mali than other West African nations, making it an extremist target, he said.KEEP UPDATED on the latest news from around the continent by subscribing to our FREE newsletter, Hello Africa.FOLLOW News24 Africa on Twitter and Facebook.The Mauritanian new agency Alakhbar said the militant group Jama Nusrat Ul-Islam wa Al-Muslimin issued a message late Saturday saying it was behind the attacks. The agency often carries claims of responsibility by jihadi groups for attacks staged across West Africa. The agency said the extremist group carried out the dual attacks in Burkina Faso in retaliation for the killing of one of its leaders in a recent raid by French troops.The group's formation, also known as JNIM, was announced in a video in March 2017 as a merger of three extremist groups: the al-Qaeda-linked al-Mourabitoun, Ansar Dine and al-Qaida in the Islamic Maghreb. It has positioned itself as the al-Qaeda branch in Mali, and Islamic State in the Greater Sahara, and has claimed attacks not only in Mali but in Niger.Several extremist groups have also vowed to step up the bloodshed in response to the recent deployment of the multinational G5 Sahel force. The 5 000-strong force combines troops from Burkina Faso, Mali, Niger, Chad and Mauritania to battle extremism in the region.Islamic extremists have carried out two other large-scale attacks on Ouagadougou in recent years, killing 30 people at a popular cafe in 2016 and 18 more at a Turkish restaurant in August 2017.Indiscriminate fury Friday's attacks killed at least eight people, including a senior officer, and left more than 80 injured.Burkina Faso's President Roch Marc Christian Kabore condemned the violence in a speech broadcast to the nation on Saturday."Nothing, absolutely nothing, can justify such indiscriminate fury against the Burkinabe state, its institutions and the brave people who love peace, democracy, justice and progress," he said.Burkina Faso's Prime Minister Paul Kaba Thieba said he is revolted by the Islamic militants' attacks and said the government and people must remain on guard."What just happened to us is a lesson, and we need to remain vigilant and also ready to anticipate on the modus operandi of the terrorists," Thieba said, announcing the government will put in place new measures to "protect institutions."The French ambassador to Burkina Faso, Xavier Lapeyre de Cabanes, expressed solidarity with Burkina Faso."Our two countries were targeted. The symbolism is strong, that is, the terrorists are trying to divide us and that will obviously not happen," he said.'It's a big shock'Security forces killed eight militant attackers, and several arrests were made after Friday's simultaneous attacks, but the repeat of violence left residents upset and in shock.Retired soldier Amado Belem told The Associated Press he is unhappy about the assault."It's a big shock to know that the army has been attacked so easily. It makes me crazy," he said.Trading resumed at the main market in Burkina Faso's capital city near the headquarters, and residents returned to the streets.Trees were burned down by the explosions and the smell of smoke lingered over the city. A deep hole in the ground and adjacent wall at the army headquarters mark where extremists dressed in uniforms set off a car bomb, apparently targeting a room where senior officers were to have met, but had relocated, according to Security Minister Clement Sawadogo.The room was completely destroyed and the car's parts scattered inside the headquarters. Sawadogo said if the meeting had taken place in that room, "our army would have been beheaded."Burkina Faso, a landlocked nation in West Africa is one of the poorest countries in the world. It shares a northern border with Mali, which has long battled Islamic extremists. Attacks have spread into Burkina Faso, and a local extremist group has also gained momentum, attacking troops and civilians.