Kabul, Afghanistan ? Authorities arrested two suspects and were seeking three others Friday in the killing of 11 Chinese road workers in northern Afghanistan, the deadliest attack on foreign civilians since the fall of the Taliban.

Farther south, insurgents launched a barrage of rockets at a heavily guarded convoy of U.N. and Afghan officials in a stronghold of Taliban-led militants, but caused no injuries.

More than 30 vehicles were picking their way through the mountains of Gomal, a lawless district in Paktika province, 140 miles south of the capital, Kabul.

“Suddenly they were attacked with rocket-propelled grenades fired from a long distance,” provincial police chief Gen. Mohammed Rahim Alikhel told The Associated Press.

Some of the dozens of Afghan and American troops guarding the convoy returned fire, and the assailants fled, Alikhel said.

The vehicles were taking Paktika Gov. Ghulab Mangal, U.N. officials and American military officers on a mission to prepare for government administrators to return to the province. Several journalists, including a contingent from ABC News, were accompanying the convoy.

Poor security has prevented the United Nations from registering voters in much of the south and east, hampering preparations for national elections slated for September.

But authorities also face growing problems in the north after Thursday’s slaughter of Chinese contractors working on a flagship road project.

Assailants crept up to the workers’ tents in a desert camp 150 miles north of Kabul and shot them as they slept. An Afghan guard was also killed.

Gen. Mohammed Daoud, the military commander in Kunduz province, said two suspects were picked up Friday in connection with the killing and three more were being sought.

He gave no details and said it was too early to say whether anti-government militants — Taliban, al-Qaida or followers of Afghan warlord Gulbuddin Hekmatyar — were responsible.

On Friday morning, Afghan and German military planes brought the dead and five wounded from Kunduz to Kabul airport.

Chinese Embassy staff helped medics carry the green plastic body bags to a line of ambulances, which took them to the morgue at the city’s military hospital. Officials said they would be taken to China over the weekend.

Four of the wounded were admitted to a hospital run by international peacekeepers. Chinese Ambassador Sun Yuxi told the AP they were all in good condition. A fifth was released.

The wife, front right, of Jiang Jiashu, one of the 11 Chinese workers slain in a terrorist attack by gunmen Thursday in northern Afghanistan, weeps upon hearing the news of the tragedy, in Guangfeng County, east China's Jiangxi Province. Two men were arrested Friday in connection with the slaughter of 11 Chinese road workers at a desert camp, an Afghan general said, in the deadliest attack on foreign civilians since the fall of the Taliban.