KABUL, Afghanistan (AP) – A suicide bomber blew himself up Sunday in an east Afghan city, killing six civilians and wounding 40 others, officials said.

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

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

An earlier bomb attack at a shop in a Khost market left a shopkeeper dead and eight people wounded, 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. The ensuing clash left five militants and a police officer dead, Paktia police chief Abdul Rahman Sarjan said.

Officers recovered five militants’ bodies alongside their weapons and one of their vehicles, Sarjan said.

In Nangarhar province, American 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.

NATO and Afghan troops are carrying out 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 to open the way for economic development, and to persuade Afghans to support President Hamid Karzai’s feeble government.