Afghan security force members stand outside a U.S. aid compound in Kunduz, northern Afghanistan, after it was stormed by militants wearing suicide vests. (Associated Press)

U.S. Gen. David Petraeus arrived Friday in Afghanistan, where he will lead American and international troops as new commander of the war.

His arrival came the same day as a deadly pre-dawn raid on a U.S. aid compound in northern Afghanistan. At least four people were killed in the attack, including at least two foreigners, officials said.

Petraeus is taking over from U.S. Gen. Stanley McChrystal, who resigned after making critical comments about the American political administration in a magazine article.

Petraeus, who had been U.S. Central Command chief, stopped at NATO headquarters in Brussels on Thursday, where he called for increased co-operation and stressed the importance of civilian-military partnerships. He also said the international mission has made progress beating back the Taliban in parts of the county, but warned that fighting in some areas will get tougher in the months ahead.

Taliban claim responsibility

The Taliban claimed responsibility for Friday's raid on the housing compound in Kunduz. A suicide bomber blew a hole in the wall around the compound used by Development Alternatives Inc., a Washington-based consulting company on contract with the U.S. Agency for International Aid (USAID). The company is working on governance and community development in the area.

At least five other attackers then ran inside the building, killing or wounding security guards and others before dying in a battle with Afghan security forces who raced to the scene.

"This complex commando-style raid sparked a six-hour firefight," journalist Tom Popyk said from Afghanistan. "Security forces inside battled the bombers as coalition forces outside treated civilian casualties and then counter-attacked."

The bodies of the victims were found amid rubble, pools of blood and broken glass. Aid workers were led from the scene as NATO troops carried bodies wrapped in black plastic out on stretchers.

No international troops were wounded in the attack, NATO said.

Gen. Abdul Razaq Yaqoubi, police chief in Kunduz province, said those killed included an Afghan policeman, an Afghan man who worked as a security guard and two foreigners. The German Foreign Ministry told The Associated Press in Berlin that a German citizen was killed in the attack.

Karzai condemns attack

Afghan President Hamid Karzai condemned the attack and called on government authorities to investigate and prosecute those responsible, saying in a statement that militants "don't want the people of Afghanistan to have a prosperous life."

"This is another tragic reminder of the life-threatening circumstances that our Afghan and international partners face every day as they work side by side with the Afghan government and its people to improve conditions in the country for a better future," said a statement issued by USAID and the U.S. Embassy.

The attack appeared to be part of a Taliban campaign against development projects at a time when the U.S. and its allies are trying to bolster civilian programs to shore up the Afghan government. On Wednesday, militants fired rockets at a base for South Korean construction workers in Parwan province but caused no casualties.

In April, a gunman killed an 18-year-old woman working for Development Alternatives as she left her job in the southern city of Kandahar. Police believed the killing was part of a Taliban campaign against Afghans working for foreign development organizations.

With files from The Associated Press