The normally peaceful Nordic nation of Norway was rocked Friday by twin attacks that left a number of people dead.

A mid-afternoon bombing that targeted the country's government headquarters in Oslo, Norway's capital, killed seven people. Hours later a gunman dressed as a police officer opened fire at a youth camp on an island off Norway's west coast, north of Oslo. Officials say at least 10 people were killed there with the death toll expected to rise.

Most of the victims were children.

Norway's Justice Minister told reporters that the man who carried out the attack on the island is Norwegian and that he is now in custody. Prime Minister Jens Stoltenberg also addressed reporters. He said what he called the “cowardly attack” will not destroy Norway's democracy or its “commitment to a better world.”

Friday's assault was the most violence Norway has witnessed since World War Two.

There has been no clear claim of responsibility, or a motive, for the attacks. But Norwegian officials have suggested they are connected.

The building that was bombed in Oslo houses the office of the prime minister but he was not there at the time and was not harmed.

U.S. President Barack Obama was quick to condemn the attacks and express his condolences for the loss of life. He said the entire international community has a stake in preventing what he called “this kind of terror from occurring.”

U.N. Secretary General Ban ki-Moon, through his spokesman, expressed his shock over learning about the attacks and said the United Nations stands with the people of Norway “at this terrible moment.”

The bombing in Oslo shattered hundreds of windows in the 17-story government headquarters building. Windows in buildings as far as 400 meters away were also destroyed. The blast sent people running through the streets in the normally quiet neighborhood which were littered with debris.