Norwegian police have begun releasing the names of those killed in last week's bombing and massacre, as the country struggles to cope with the tragedy.

Police Tuesday named the first four of the 76 victims — three who were killed in the bomb blast in the capital, Oslo, and one in the shooting rampage at an island youth camp.

The defense lawyer for the Norwegian suspect, Anders Behring Breivik, says the case suggests his client is insane.

Earlier Tuesday, during a news conference in Oslo, defense attorney Geir Lippestad said Breivik, who has confessed to Friday's massacre, is not aware of the death toll nor of the public response to the attacks. Lippestad told reporters it is too early to say if his client would plead insanity.

Police Tuesday detonated a cache of explosives found at a farm Breivik rented about 160 kilometers north of Oslo. Breivik reportedly used the farm as a cover for ordering the six tons of fertilizer he used to make his bomb.

While Breivik has admitted responsibility for the attacks, he has pleaded not guilty to the terrorism charges, claiming he acted to save Europe from what he says is Muslim colonization.

In Washington, U.S. President Barack Obama visited the residence of the Norwegian ambassador to personally offer his condolences for the innocent victims of the twin attacks. Accompanied by Vice President Joe Biden, Mr. Obama said he was heartbroken by the tragic loss of life, and reassured the Norwegian people that the United States stands with them.

Mr. Obama on Saturday condemned the “senseless” attacks, calling the tragedy a reminder that the world has a stake in stopping such acts of terrorism.

Lippestad Tuesday said his client told him he took drugs to be “strong, efficient, awake.” The lawyer added Breivik claims to be part of an anti-Islam network that has two groups in Norway and several more abroad. But Norwegian police and researchers have cast doubt on such claims. Police say they believe Breivik acted alone.

Earlier, Norway Justice Minister Knut Storberget praised police for their response to the attacks Friday, saying officers did “fantastic” work.

His comments follow criticism in the media about how long it took police to reach the camp on Utoeya Island, where Breivik is accused of killing at least 68 people. Police have said it took more than an hour for officers to get to the site.

The suspect's father, retired diplomat Jens Breivik, told reporters in France that he feels shame and wishes his son had killed himself instead.