OSLO (Agencies) - The Norwegian capital Oslo was struck Friday by two terrorist attacks, a car bombing near government offices in the city centre and a shooting at an island youth camp. Police said seven people were killed in the bombing and witnesses reported 25 dead at the camp. The huge car bomb exploded in mid-afternoon and, in addition to the fatalities, a number of people were wounded. In addition to those hospitalised, a hospital spokesmen estimated that a hundred people, maybe more were walking wounded. A few hours later, a man wearing a police uniform opened fire at a youth camp on an island outside the capital. The youth wing of Prime Minister Jens Stoltenbergs Labor Party was holding an annual meeting at the camp at Utoeya, and the prime minister had been scheduled to attend on Saturday. Witnesses said some teenagers leaped into the sea to swim to safety after the shooting started, while others took refuge in caves or behind bushes. Police said the gunman, described by witnesses as tall and blond, had been arrested. One witness said the gunman arrived on the island claiming to be part of the security forces protecting the camp, then produced a handgun and opened fire. Army units took up positions around central Oslo following the two incidents. A terror group, Ansar al-Jihad al-Alami issued a statement claiming responsibility for the attack, according to Will McCants, a terrorism analyst at the American CNA, a research institute that studies terrorism. The statement said the attack was in response to Norwegian forces presence in Afghanistan and to insults against the Holy Prophet Muhammad (PBUH). We have warned since the Stockholm raid of more operations, the group said in apparent reference to a bombing in Sweden last December. What you see is only the beginning, and there is more to come. The claim could not be verified. There have been previous threats against Norway, but political violence has been almost unknown in a country renowned for sponsoring the Nobel Peace Prize and mediating in conflicts ranging from the Middle East to Sri Lanka. The bombing blew out windows in a 17-story modern building housing the prime ministers office, set fire to the Oil Ministry across the street and left broken masonry, glass and twisted steel girders littering the street. The mangled remains of an overturned automobile lay amid the debris. Authorities said Prime Minister Stoltenberg was safe, as he had been working at home instead of in his office at the time of the mid-afternoon blast. Norwegians work short hours in the summer and many were on summer holidays, so there were fewer people on the streets and in office buildings than would normally be the case at that time of day. This is very serious, Stoltenberg told Norwegian TV2 in a phone call. He said it was too early to say if the bombing was a terrorist attack. Police had advised him not to say where he was speaking from. Even though we have prepared for this type of situation, it is fairly dramatic when it happens, he said. He urged Norwegians not to cave in to fear and he called a crisis meeting of his Cabinet to discuss the situation. President Barack Obama and other leading figures around the world condemned the attacks. Norwegian State Secretary Kristian Amundsen told the BBC in London that some people were trapped in buildings hit by the bombing. I cant go into details, he said. A Reuters reporter said he saw eight people injured, one covered in a sheet and apparently dead. A press officer at Oslo University Hospital said seven injured people had been admitted there. Later police said 15 people had been injured. Oslo, a city of 1.4 million population, is a relatively easy target for terrorists. Residents interviewed after the bombing on Friday said security is fairly light around the government buildings that appeared to be the focus of the attack, with no restrictions on driving and parking cars in front of them. It is the fastest-growing city in Europe, due mostly to an influx of immigrants. About 25 per cent of the population is composed of immigrants. Speculation about those behind the bombing cantered on several groups, all with Middle East affiliations. One prime source of grievance for such groups is the fact that Norway has about 500 troops taking part in military operations in Afghanistan. Al Qaeda has threatened retaliation unless the troops are withdrawn. Less likely to be the cause of the bombing is Norwegian participation in the NATO bombing campaign in Libya. The government announced in June that it was reducing the number of fighter jets involved from six to four and would withdraw completely by Aug. 1. A third possibility is that the bombing is retaliation for the 2010 publication in the Oslo newspaper Dagbladet of a blasphemous cartoon. The publication brought out large-scale protests by Muslims, with 1,000 Muslim taxi drivers using their cars to block streets in central Oslo in February last year. Dagbladet said it had published the cartoon not to provoke Muslims but to illustrate that the Facebook profile of the Police Security Service contained links to the blasphemous cartoons. These are not the same cartoons that a Danish newspaper, Jyllands-Posten, published in 2005 and that brought demonstrations against Danish embassies in several Middle East capitals as well as death threats and attempts against the cartoonist, Kurt Westergaard. Yet another possibility is that the bombing was linked to a controversy over Mullah Krekar, founder of the Kurdish armed Islamist group Ansar al-Islam. Norwegian prosecutors filed a terrorism charge against him on Tuesday after he threatened a former minister, Erna Solberg, with death if he is deported. He came to Norway as a refugee from northern Iraq in 1991. His wife and four children have Norwegian nationality but he does not. His birth name was Najmuddin Faraj Ahmad. Brian Paddick, a former deputy assistant commissioner of London police, who had been planning to travel to Oslo on Friday, told the BBC that police there have had problems recently with armed Pakistani gangs but he did not know if they were involved in the violence. The city has a significant Pakistani population, he said.