Militants killed six Americans, including a young female diplomat and an Afghan doctor, in a pair of attacks in Afghanistan on Saturday. It was the deadliest day for the United States in the war in eight months.

The violence — hours after the U.S. military’s top officer arrived for consultations with Afghan and U.S.-led coalition officials — illustrates the instability plaguing the nation as foreign forces work to pull nearly all their combat troops out of the country by the end of 2014.

The attacks came just days after insurgents stormed a courthouse, killing more than 46 people in one of the deadliest attacks of the war, now in its 12th year.

The three U.S. service members, two U.S. civilians and the doctor were killed when the group was struck by an explosion while traveling to donate books to students in a school in the south, officials and the State Department said.

In a statement, Secretary of State John Kerry said the Americans included a department of defense civilian and foreign service officer.

“She tragically gave her young life working to give young Afghans the opportunity to have a better future,” Kerry said. “We also honor the U.S. troops and Department of Defense civilian who lost their lives, and the Afghan civilians who were killed today as they worked to improve the nation they love.”

Officials said the explosion occurred just as a coalition convoy drove past a caravan of vehicles carrying the governor of Zabul province to the same event.

Another American civilian was killed in a separate insurgent attack in eastern Afghanistan, the U.S. military said in a statement.

It was the deadliest day for Americans since Aug. 16, when seven American service members were killed in two attacks in Kandahar province, the birthplace of the Taliban insurgency. Six were killed when their helicopter was shot down by insurgents and one soldier died in a roadside bomb explosion.

The latest attacks occurred just hours after U.S. Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, landed in Afghanistan for a visit aimed at assessing the level of training that American troops can provide to Afghan security forces after international combat forces complete their withdrawal.

A U.S. official who spoke on condition of anonymity said several other Americans and Afghans, possibly as many as nine, were wounded. The State Department said four of their staff were wounded, one critically.

Taliban spokesman Qari Yousef Ahmadi claimed responsibility for the attack in Zabul and said the bomber was seeking to target either a coalition convoy or the governor.

“We were waiting for one of them,” Ahmadi said in a telephone interview with The Associated Press. “It was our good luck that both appeared at the same time.”

The deaths bring the number of foreign military troops killed this year to 30, including 22 Americans. A total of six foreign civilians have died in Afghanistan so far this year, according to an AP count.

Provincial Gov. Mohammad Ashraf Nasery, who survived the attack in Qalat, said the explosion occurred in front of a hospital and a coalition base housing a provincial reconstruction team, or PRT. International civilian and military workers at the PRT train Afghan government officials and help with local development projects.

Nasery said the car bomb exploded as his convoy was passing the hospital. He said the doctor was killed, and two of his bodyguards and a student from the school were wounded.