Schoolgirls who survived a bloody bus hijacking sang hymns Thursday at a Mass celebrated by Pope John Paul II but still felt the terror from the night before, when police stormed the bus in a hail of bullets. One survivor said the hijackers, opposed to the military government, sang and prayed with the 71 hostages before shooting at the captives and lobbing grenades when police moved in to end the 27-hour ordeal on Wednesday night. Three hijackers and a 14-year-old girl were killed immediately. On Thursday, a second passenger died of a bullet wound to the head and the fourth hijacker died, the South African Broadcasting Corp. said. Officials said 20 people were injured by bullets and by shrapnel from the hijackers' grenades. Some of the hostages said they saw the hijackers setting up some type of explosive device. The independent South African Press Association, quoting ``well-placed sources who watched the saga at close range'' said a explosive device, to be triggered electronically, was found fixed to the door of the bus. The government, which earlier denied South African forces were invited to help end the hijacking, said South African police and Lesotho soldiers assaulted the bus after the gunmen ordered the driver to crash into the grounds of the British High Commission, or embassy. Vitilina Quoaoho, 18, said the hijackers ``told us to lay under the chairs and they ordered the driver to pass through the locked gate'' of the embassy. ``We saw a big light (a flare fired by police) and then the soldiers started shooting at the bus and the men (the hijackers) were shooting at us,'' she said. ``We were very frightened. We are still frightened,'' she said, with her friends echoing her words. As they spoke, men and women, singing hymns to the beat of drum, walked by to take communion during a brief, sunny moment in a Mass that had been punctuated by thunder, rain and cold winds. The schoolgirls and several nuns who were aboard the bus were among a crowd of about 15,000 who gathered at the Maseru racecourse to see the pope beatify a French missionary who worked in Lesotho until his death in 1914. Four of the girls, wearing plastic bags as rainhats and blue uniforms from Pope John XXII High School, said that during the hijacking police appeared ready several times to fire at the bus during the journey to Maseru from the hijack point at Quacha's Neck. ``The men (the hijackers) prevented them, saying, `If you shoot you will be shooting your own people,' '' said one of the girls. One unanswered question was why the hijackers suddenly tried to force the bus into the British embassy compound. It happened less than a half hour after the pope's motorcade, with police escort, had driven through the capital. He arrived by road from South Africa, where his plane was diverted due to bad weather in Maseru. Monica Morori, 36, who injured her feet jumping from the bus's shattered windows during the shootout, said the hijackers were joining passengers in singing and praying. Two of the hijackers were in their late teens and two were grown men. After the Mass, the pope rode through the capital's main street to the Queen Elizabeth II hospital, where he gave medals and crucifixes to some of the injured, including children and two nuns. The pope urged his followers at Thursday's youth rally to ``renounce every form of violence and hatred.'' ``The increase of violence in the world can never be halted by responding with more of the same,'' he said. In an apparent criticism of some militants, including activists who contend passive resistance alone cannot overcome South Africa's system of racial segregation, John Paul said: ``There could be nothing further from the truth. There is nothing passive about non-violence.'' The pope commented Thursday on the bus hijacking, remarking, ``I am saddened to learn that others on their way to join me on this pilgrimage have been victims of a hijack that has caused such anguish and ended in bloodshed.'' One of the nuns he visited, Sister Florina Nyogar, who had a bruised face, later told a reporter how she felt during the shooting. ``We saw that it was our end, and we accepted to die,'' she said. She said reports from the government that the hijackers refused to accept food for the hostages were inaccurate. ``We didn't feel like eating or drinking, we only felt like praying,'' she said. Several hostages said the hijackers, who brandished a Soviet-designed AK-47 automatic rifle, pistols and hand grenades, claimed to be members of the Lesotho Liberation Army, a dissident group that for years was based in South Africa but staged few operations. Lesotho's ruling military council also blamed the dissident group for the hijacking. The group's political commissar, Matladi Sehlabaka, told The Star newspaper of Johannesburg that his organization was not responsible. ``We could not have undertaken such an operation because we are on talking terms with the Lesotho regime,'' Sehlabaka said. The hijackers reportedly demanded an end to military rule and asked for a meeting with the pope and King Moshoeshoe II. The organization was also opposed to the leftist government of the late Prime Minister Leabua Jonathan, who was ousted by the current military council in a bloodless coup in January 1986.