KABUL, Afghanistan – Militants killed 17 Afghan police officers across Afghanistan, while four suspected Taliban fighters died in a clash with NATO and Afghan troops, officials said Wednesday.

Six police officers were killed when their convoy was ambushed along the Kabul-Kandahar highway, a ribbon of road that connects Afghanistan’s two major cities. Long stretches of Highway 1 run through areas controlled by Taliban militants.

Taliban fighters also ambushed police in Logar province, killing six officers and stealing two police trucks, said Gen. Mustafa Khan, the provincial police chief. Most of the attackers fled when NATO and Afghan reinforcements arrived, but eight militants were captured, Khan said.

In the east, two suicide bombers tried to attack Khost’s provincial police station. One bomber blew himself up and killed at least three officers, while the second bomber was shot and killed without causing casualties, said Mohammad Wali Shah, provincial police chief.

Suspected Taliban militants ambushed two police officers riding a bicycle in Zhari district in southern Kandahar province Tuesday, killing both, said Sayed Agha Saqib, the provincial police chief.

Five policemen also were wounded in the southern Zabul province, said Gen. Yaqoob Khan, the provincial police chief, and two vehicles were damaged.

NATO-led and Afghan troops, meanwhile, clashed with Taliban fighters in Kandahar province, leaving four militants dead, Saqib said.

In other violence, gunmen on a motorcycle killed an employee of the International Rescue Committee, a humanitarian and development organization that has been working in Afghanistan since 1980. The gunmen overtook the vehicle carrying Akram Mohammad Gul, a social organizer for the IRC and father of seven, the IRC said. The driver of Gul’s car, Mustafa Sayed Abdullah, was also killed in the attack in Logar.

A suicide bomber targeted a convoy of Turkish vehicles on Kabul’s outskirts, injuring one Afghan civilian and a Turkish soldier, officials said. The explosion hit a vehicle with diplomatic license plates, but its occupant wasn’t immediately known.

An attack on a road construction crew in Paktia province killed one Filipino and wounded three guards, said Ghulam Dastager, the province’s deputy police chief.

Violence has spiked in Afghanistan recently. More than 3,300 people have died in insurgency-related violence this year, according to an Associated Press count based on Afghan and Western official numbers.

NATO said five advanced roadside bombs had been found in Afghanistan this year. Two were found unexploded in Herat and two in Kabul, while one detonated in the capital. Col. Thomas Kelly, a NATO officer responsible for countering such weapons, said the technology was probably foreign.

Meanwhile, the top U.S. general visited Afghanistan on Wednesday and told troops he had seen a “sea change” that made him optimistic.

Marine Gen. Peter Pace, chairman of the Joint Chiefs of Staff, said progress in the almost six-year-old war included a “very, very healthy” percentage of children attending school and “a functioning central government and legislature that are trying to do the right things.”

He added that Afghanistan’s national army is fighting “very well.”

Compared to Iraq’s sectarian violence, Pace said, “Afghanistan’s societal approach to defeating the enemy is much more homogeneous and therefore it’s a step ahead as far as being able to pull the nation together, keep it tied together and get on down the road.”

Nevertheless, he told troops at the U.S. base in Bagram, militants represents a serious threat, with Taliban and al-Qaida fighters conducting operations out of havens along the mountainous frontier between Afghanistan and Pakistan.

“This is not without future problems, but I’m very optimistic here in Afghanistan about what we have accomplished with the Afghan government today, what we’re capable of accomplishing in the future,” Pace said.

Associated Press writer Noor Khan in Kandahar contributed to this report.

A service of the Associated Press(AP)