Abuja: A car laden with explosives rammed through two gates and blew up at the United Nations’ offices in Nigeria’s capital Friday, killing at least eight people and shattering part of the concrete structure.

The brazen attack, carried out as the U.N. offices teemed with staff, comes as Africa’s most populous nation faces the growing threat of both homegrown and international terrorism. Militants from a radical Muslim sect from northeast Nigeria have carried out attacks in the country’s capital, though never on a foreign target. The country’s oil-rich Niger Delta in the south has also spawned a violent militant group.

Witnesses told The Associated Press that a sedan rammed through two separate gates at the U.N. compound as guards tried to stop the vehicle. The suicide bomber inside crashed the car into the main reception area and detonated the explosives, inflicting the most damage possible, a spokesman for the Nigerian National Emergency Management Agency said.

“I saw scattered bodies,” said Michael Ofilaje, a UNICEF worker at the building, which he said shook with the explosion. “Many people are dead.”

The building houses about 400 employees of the U.N. in Nigeria, including the majority of its offices. A local U.N. spokesman declined to comment, but a local hospital administrator told the AP it had treated as many as 40 victims so far, with more people coming in.

Eight bodies of victims were brought to the morgue of the nearby National Hospital, spokesman Payo Hastrup said. Local television stations broadcast pleas for blood donation. Officials tried to account for everyone inside the building at the time of the explosion.

“We believe there are many casualties but at this point we don’t know what the level of casualties is,” U.N. deputy spokesman Farhan Haq said in New York. “We condemn all terror attacks regardless of motivation.”

The building, located in the same neighborhood as the U.S. embassy and other diplomatic posts in Abuja, houses offices of a number of U.N. agencies including the U.N. Development Program, UNICEF and the U.N. Population Fund.

The explosion punched a huge hole in the building. Workers brought three large cranes to the site within hours of the attack, trying to pull away the concrete and rubble to find survivors. Others at the site stood around, stunned, as medical workers began carrying out what appeared to be the dead.

“This is getting out of hand,” said a U.N. staffer who identified himself as Bodunrin. “If they can get into the U.N. House, they can reach anywhere.”

Ali Tikko, who was in a building 100 yards (meters) from the site of the blast when it occurred said, “I heard one big boom.”

“I see a number of people lying on the floor — at least four or five. I cannot see if they are dead. There are a lot of security around,” Tikko said by telephone.

Local police spokesman Jimoh Moshood said police are investigating. Reuben Abati, a spokesman for President Goodluck Jonathan, said the presidency would later issue a statement on the attack.

No one immediately claimed responsibility. Oil-rich Nigeria faces terrorism threats on multiple fronts.

Nigeria, a nation of 150 million, is split between a largely Christian south and Muslim north. In recent months, the country has faced an increasing threat from a radical Muslim sect called Boko Haram, which wants to implement a strict version of Shariah law in the nation. The sect has carried out assassinations and bombings, including the June car bombing in Abuja of the national headquarters of Nigeria’s federal police that killed at least two people.

Earlier this month, the commander for U.S. military operations in Africa said Boko Haram may be trying to link with two al-Qaida-linked groups in other African countries to mount joint attacks in Nigeria.

Gen. Carter Ham told AP on Aug. 17 during a visit to Nigeria that “multiple sources” indicate Boko Haram made contacts with al-Qaida in the Islamic Maghreb, which operates in northwest Africa, and with al-Shabab in Somalia.

“I think it would be the most dangerous thing to happen not only to the Africans, but to us as well,” Carter said.

Last year, a militant group from the country’s oil patch, the Niger Delta, blew up car bombs in the capital during Nigeria’s 50th independence anniversary ceremony, killing at least 12. The militant group did not immediately respond to an AP request for comment Friday.