New videos from the moment of the blast in Oslo and its immediate aftermath have continued to emerge as Norway struggles to cope with scale of Friday’s devastating violence.

A closed circuit camera captured the force of the bomb’s shock as it ripped through the center of the city, blowing out shop windows and knocking over merchandise with the apparent force of an earthquake.

As the Norwegian national broadcaster NRK reports, the above footage came from a surveillance camera in an electronics store, Digital Impuls, which is located near Grubbegata, the Oslo street lined with government buildings where the blast was detonated. Nikolai Skoglund, an employee, said he knew it was an explosion and not an earthquake after emerging from the store to smell a strange odor and seeing a cloud of smoke and dust.

The extent of the damage to the main government building, an imposing 17-story structure on a large plaza, and others around it is visible in a dramatic, and at times very graphic, video by Johan Christian Tandberg of the moments after the explosion.

Mr. Tandberg, who works in real estate in Oslo but studied journalism at the University of Utah in the 1990s, said in a telephone interview that he was driving through a tunnel under the government plaza at the moment of the blast.

“I thought the roof was going to come down, and drove out really quickly from the tunnel,” he said. He began recording the 16-minute video only seconds later. “I thought maybe I could catch something on the tape that could help the police afterwards,” he said. “I act on autopilot.”

In the video, Mr. Tandberg moves through the debris from the back of the large main building, to the front, where the bomb blast was strongest, capturing stupefied survivors pacing around in shock as well as bloody images of some of the wounded on the ground.

“It just went on and on and I saw more and more of the scale of this bomb,” he said. “Most of the people had lost their hearing.”

His video provides rare footage of the inside of the damaged main building, which Mr. Tandberg entered in search of survivors. “Thanks to god it was vacation. I was thinking, if somebody was here, they would be dead.”

At a news conference on Wednesday the prime minister, Jens Stoltenberg, was asked when officials could be expected to return to the heavily damaged government buildings, including his own office, that were the target of the bombing. He responded that it was too early to say when — or if — everyone would return to the buildings or some would move permanently.

As this ITN video shows, Mr. Stoltenberg said that Norwegians “want in a way to defend themselves from violence by showing that they are not afraid of violence.”

The prime minister also hailed what we called “the strong message from Norwegians going into the streets on Monday, when we had hundreds of thousands of Norwegians marching with flowers, with roses, and all uniting in the same message — of not being afraid and not being intimidated by the violence.”

Some have questioned the response time of police to Utoya island, where 68 people were killed at a political camp. The police told NRK that they were seconds away from shooting the suspect, Anders Behring Breivik, 32, a self-declared warrior for Christian values, when he surrendered. He immediately claimed responsibility for the attacks.

NRK previously posted video that shows police moving onto Utoya from small boats. At a news conference on Wednesday, police did not explain why they relied on cars and boats to reach the island as television helicopters beat them to the scene.

As authorities began confirming the names of those killed, video emerged of the Utoya camp, an annual gathering of young Labor Party members, that was shot on the island shortly before before the rampage. It was posted Thursday on the Labor party’s YouTube channel, and shows Jonas Gahr Store, the country’s foreign affairs minister, as well as many campers. For the moment, it remained unclear if any of those who appear in the video were among the dead. The Guardian has provided an interactive graphic of those who have been identified so far.