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 . 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 . The explosion happened in central London , popular among tourists .
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 .