Ghana mourned on Thursday for at least 120 people killed in Africa's worst football tragedy, the soccer-mad continent's third deadly stadium disaster in a month. Authorities promised an inquiry into the stampede, wich spectators said was triggered by police firing teargas after fans hurled missiles at the end of Wednesday's game between two of Ghana's leading teams, the arch-rivals Hearts of Oak and Asante Kotoko. "I have set up an internal probe to investigate this tragedy. We're not going to shield anybody," Ghana's top police officer, Inspector General Ernest Owusu-Poku, told local Joy FM Radio. President John Kufuor summoned his cabinet for an emergency meeting later on Thursday and his aides said that a period of national mourning would be declared. Kufuor, who was once Kotoko's club chairman, was clearly very shaken during a visit to the injured at the military hospital in the capital Accra. He told Reuters simply: "This is really sad." An aide said the president had screamed when he first heard the news. Brigadier Daniel Twum said 102 dead were brought to the military hospital and officials at two other hospitals confirmed a further 18 dead. "Some died of suffocation but the majority seem to have been killed by being crushed," Twum said. He said another 50 people had been injured, but most were not in serious condition. TEARGAS IN PACKED STADIUM Witnesses said that with Hearts of Oak leading 2-1 after two quick goals near the end of the game, Asante Kotoko fans began throwing chunks of their plastic chairs onto the pitch. Police reacted by firing teargas, triggering a stampede for the exits in the packed stadium, which can hold 50,000 people. Wails of anguish echoed around the stadium as scores of bodies piled up from Africa's third football disaster in the last month and the worst in its history. On April 11, 43 soccer fans were crushed to death when fans tried to force their way into Johannesburg's huge Ellis Park stadium midway through a top South African league match. At least seven people were killed and 51 seriously injured in an April 30 stampede in the Democratic Republic of Congo after police moved to break up rioting at a match in Lubumbashi. Bitter rivalry has long marked games between Hearts of Oak and Asante Kotoko, two of the biggest names in African football. Hearts of Oak's following is from Ghana's coastal capital Accra. Kotoko draws its support from the old Ashanti kingdom where Kufuor has his roots. Fears of trouble at one of the first matches in the league this season had meant there was a heavy police presence at the Accra Sports' Stadium. Harry Zakour, chief executive of Hearts of Oak, criticised police for firing up to a dozen teargas canisters in the stadium. "One would have been enough to scare the public," he said. "It's a very sad story. We will have to set up a committee to see what went wrong". Kotoko's chairman, Herbert Mensah, said "it's inappropriate at this time to indulge in finger-pointing." Africa, which hopes to host the 2010 World Cup despite concerns over stadium safety, has suffered repeated tragedy over the past decade as a result of soccer violence. Thirteen people died last year in a stadium stampede in Zimbabwe after police fired teargas. In 1996, at least seven people were killed during a stampede in Zambia. Forty people died outside Johannesburg in 1991 after being crushed against a stadium fence, trampled underfoot or stabbed as thousands of fans surged towards a jammed exit to escape rival brawling spectators.