MOGADISHU, Somalia -- The massive truck bomb that killed 15 people, including a Kenyan diplomat, and wrecked Somalia's premier hotel has stunned the capital and raised fears Monday that the Islamic extremist al-Shabab rebels are escalating their violence.

Senior police official Capt. Mohammed Hussein said the toll has risen to 15. "This is a very worrying situation," he said as he stood outside the Hotel Jazeera near a dead body. "This happened despite all the security precautions in place."

In a visit to neighbouring Ethiopia, U.S. President Barack Obama said Monday the bombing is a reminder "we have more work to do" in stemming terrorism in the region and that groups like al-Shabab offer nothing but destruction.

The scene at the site was grisly, with the front sheared off of the five-story luxury hotel that once housed diplomats, journalists and visiting heads of state. The damage echoed the decades of conflict in Mogadishu that once left much of the city as rubble.

Desperate relatives searched the bloodstained rubble with their bare hands looking for survivors while to the side lay a large sack of body parts.

The bomb was made of a ton of explosives and destroyed dozens of nearby homes, said police.

"It's a criminal and cowardly act but that will not disrupt our struggle toward peace," Somali Foreign Minister Abdisalam Omer told The Associated Press by phone from Djibouti.

The U.N. Security Council condemned the attack "in the strongest terms."

The toll from the attack including a Kenyan diplomat, a Chinese embassy guard and two journalists, Abdihakin Mohamed Omar, a producer for Somali Broadcasting Corporation and Mohamed Abdikarim Moallim Adam, a reporter for the London based Universal television, who were driving near the hotel at the time of the attack.

Authorities say that the toll could have been much higher since the truck exploded outside the hotel's blast walls, but bombs of such magnitude are a new phenomenon.

Security officials link the attack to setbacks by al-Shabab in the field where they have been driven out of Mogadishu and strongholds in the countryside by combined African Union and Somali forces.

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A previous version of this story has been corrected to show the number of journalists killed in the attack is two, rather than three.