Casablanca , Morocco ( CNN ) -- A series of explosions that killed 15 people when they erupted Thursday morning in a cafe in the city of Marrakech was an act of terrorism , Morocco 's interior minister said . `` We will investigate this act of terrorism and find those responsible ... and their nationality , '' Taib Cherqaoui told reporters about the attack , in which at least 22 others were wounded . `` We condemn it as a criminal act . '' In an address on state-run television , Cherqaoui and King Mohamed VI said the fatalities included six French nationals , five Moroccans , and four others whose nationalities were not divulged . CNN has learned that , of the four remaining fatalities , two were Russian and one was British . The incident occurred around 11 a.m. at Cafe Argana in Marrakech 's old city , which is designated by the United Nation 's cultural arm as a World Heritage Site . Tourists flock to it in high numbers this time of the year and it is usually packed with stalls , story-tellers and snake-charmers . World leaders moved quickly to condemn the incident . U.N. Secretary-General Ban Ki-moon was `` appalled , '' according to a statement from his office . `` He reiterates his firm rejection of the use of indiscriminate violence against innocent civilians and maintains that no political objective justifies or is served by such heinous acts . '' U.S. Secretary of State Hillary Clinton said the United States `` condemns in the strongest terms today 's terrorist attack , '' adding , `` Acts of terrorism must not be tolerated wherever and whenever they occur . '' French Foreign Minister Alain Juppe condemned what he called a `` barbarian terrorist attack , which nothing can justify . '' `` Such an awful act can only bring indignation and unreserved condemnation . All light must be shed on this revolting crime , officials prosecuted , tried and punished , '' said Juppe , who said French authorities will provide assistance to French nationals in Marrakech . `` We were walking around the souks , right around the corner from Cafe Argana , '' said a German tourist who was about 50 meters from the blast when it occurred . `` We heard a gigantic boom , and everyone immediately starting running towards the square to see what happened . '' The woman , who did n't want her name used , told CNN the top floor and terrace of the cafe were `` ripped apart '' by the blast , which caused hundreds of people to run from the area . It was not immediately known whether the attack was linked to unrest across the Arab world or militant activity , although there have been protests in Morocco lately . The blast comes four days after thousands of Moroccans held a peaceful demonstration nationwide , calling Sunday for a radical overhaul of the country 's governance before a new constitution is unveiled in June by King Mohammed VI . The march was organized by the Facebook youth movement Fevrier 20 . The group said its members would not accept the draft constitution because it was written by the king 's own people . It denounced his decision to refer the new constitution to a committee he appointed . King Mohammed announced last month he would give up some of his wide-scale powers and make the judiciary independent -- the latter a particularly hot subject in Morocco . Calls for an end to political detention and questions about the king 's personal business activities were also on protesters ' banners . There was visible resentment at the royal family 's business operations , controlled by its holding company SNI . There were also groups protesting about the prices of basic household items . Since the Casablanca attacks of 2003 , in which 33 bystanders and 12 suicide bombers were killed , the Moroccan government has impressed international officials for breaking up Islamic terrorist cells . For example , the Madrid train bombings in 2004 , in which 191 people died , were assisted by a Moroccan group of terrorists -- 19 of whom are serving sentences in Moroccan prisons . CNN 's Mitra Mobasherat and Journalist Martin Jay contributed to this report .
NEW : U.N. Secretary - General Ban Ki - moon ` ` appalled , '' his spokesperson says . ` ` We will ... find those responsible , '' interior minister says . A tourist heard a loud boom and saw the damaged terrace . The explosion happened in central London , popular among tourists .