A homicide bomber blew himself up Sunday in an eastern Afghan city, killing six civilians and wounding 40 others, officials said, while a roadside blast hit an Afghan intelligence service vehicle, killing all four people in the car.

The remote-controlled roadside bomb killed two intelligence service officers, a soldier and their driver, said Laghman provincial police chief Abdul Karim. The attack took place in the provincial capital, Mehtar Lam.

"The enemy is not brave enough to fight face-to-face with the Afghan army," Karim said. "They have to resort to suicide and roadside bombs."

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Police, acting on a tip in the eastern city of Khost, tried to stop a suspicious looking man, said provincial police chief Gen. Mohammad Ayub. When he tried to flee, police chased him and opened fire, at which point he detonated his explosives, Ayub said.

Khost public health director Gul Mohammad Mohammadi said six civilians were killed and 40 others were wounded, most of them with minor injuries. Fifteen people suffered serious injuries and were hospitalized, he said.

Ayub said two policemen were also wounded.

An earlier bomb attack at a shop in a Khost market killed a shopkeeper and injured eight people, Ayub said, describing the incident as a dispute between different tribes.

In neighboring Paktia province, suspected Taliban militants ambushed a police patrol Saturday in the Zormat district, and the ensuing clash left five militants and a police officer dead, said Paktia police chief Abdul Rahman Sarjan.

Officers recovered five militants' bodies with their weapons and one of their vehicles, Sarjan said.

In Nangarhar province, U.S. and Afghan troops killed one person and detained nine others during a raid on a compound Saturday, the U.S.-led coalition said in a statement.

The compound was used by people the coalition accused of involvement in "facilitating" several suicide attacks in recent weeks.

"During the operation, a militant grabbed a weapon and was shot and killed by combined forces," the statement said.

The latest violence came as NATO and Afghan troops pushed forward with their largest-ever offensive launched last month in southern Afghanistan to flush out Taliban militants from the northern tip of opium-producing Helmand province.

Scores of militants have been killed in a campaign aimed at facilitating economic development, and to persuade Afghans to support President Hamid Karzai's feeble government.