No Americans were killed or injured in the blast on the outskirts of Jalalabad, whose airport also is home to a Western military base, an official with the international coalition said. The dead were Afghan civilians and security personnel, said police spokesman Hazrat Mohammad Zamari.

The grenade attack Sunday in Kunduz province, in the country’s north, came on the sixth day of protests over Korans being sent, apparently by accident, to the trash incinerator at a base north of the Afghan capital. The violence has left nearly 40 people dead, including four American service members, but the scope of the protests appeared to be narrowing after President Hamid Karzai went on national television and appealed for calm.

Officials in Kunduz province blamed “agitators” sheltering among the crowd of protesters for the grenade attack in the Imam Sahib district. In the past, insurgents have used large-scale demonstrations to slip gunmen into crowds.

Meanwhile, the Afghan Interior Ministry acknowledged Sunday that one of its workers was the key suspect in the deaths of two American military officers who were gunned down at their desks in a tightly guarded command-and-control center a day earlier.

That attack on Saturday prompted the commander of the NATO force in Afghanistan, U.S. Gen. John R. Allen, to take the unprecedented step of immediately pulling Western military advisors out of Afghan government ministries. The incident called into question Western willingness to continue training and advising Afghan troops and government bodies amid an unrelenting spate of turncoat shootings.

The suspect remained at large, the ministry said in a statement, adding that “serious efforts by Afghan security forces are underway to capture him.”

For the North Atlantic Treaty Organization force, the attack was particularly worrisome because it involved an individual with access to highly sensitive information. Afghan officials said the suspect was a 25-year-old intelligence officer who had obtained the code needed to enter the restricted area where the two U.S. officers were working. Officials said the two were shot in the back of the head.

U.S. Ambassador Ryan Crocker said Sunday in a television interview that the outbreak of violence and the resulting American deaths should not lead to any precipitous decisions about the pace of the drawdown of Western troops.

“This is not the time to decide that we’re done here,” the ambassador told CNN.

“We have got to redouble our efforts. We’ve got to create a situation in which Al Qaeda is not coming back.”

Yaqubi is a special correspondent.