Kabul, Afghanistan (CNN) -- Afghan security forces stormed a bank branch besieged by insurgents in Helmand province Wednesday, ending a deadly attack, police said.

Five civilians, one police officer and two army soldiers were killed, said Farid Ahmad Obaid, a spokesman for the police chief of southern Helmand province.

Fourteen others, nine civilians among them, were wounded, Obaid said. He warned that the death toll could go up since at least one of those injured was in critical condition.

The Taliban claimed responsibility for the attack on the Kabul Bank office in the provincial capital of Lashkar Gah.

Taliban spokesman Qari Yousuf Ahmadi said via Twitter that the target was Afghan security forces personnel who were visiting the bank to receive their monthly salary.

All the attackers were killed in the operation to end the siege, Obaid said.

The four armed insurgents attacked shortly before noon, he said. The first attacker, who was riding a motorbike, blew himself up outside the bank branch, while three others stormed inside the building, he said.

Obaid said the gunbattle between the Afghan security forces and the assailants lasted about 90 minutes before the militants were killed.

Meanwhile, a suspected drone strike Tuesday killed 11 Taliban in Afghanistan's eastern Nangarhar province, near the border with Pakistan, a local Afghan government official told CNN on Wednesday.

Among those killed in the strike in Sherzad district were four Pakistanis and two midlevel Afghan Taliban officials, said Malem Mashuq, the district chief.

It's not clear if the strike was linked to Tuesday's shocking attack by the Pakistan Taliban on an army-run school in Peshawar, northwestern Pakistan, in which 145 people were killed, 132 of them children.

Analysts say the Afghan and Pakistan Taliban groups are closely affiliated, often sharing resources and jointly plotting attacks on either side of the porous border.

However, a spokesman for the Afghan Taliban condemned the Peshawar attack Tuesday because it involved the "deliberate killing of innocent people, women and children."

Separately, two bomb explosions Wednesday morning in Nangarhar's capital city, Jalalabad, targeted Afghan police vehicles, killing two Afghan policemen and injuring five others, said Zia Abdulzai, a spokesman for the provincial governor.

The continuing violence comes as Afghan security forces prepare to take on greater responsibility for ensuring the country's security as international forces transition to a supporting role.

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CNN's Masoud Popalzai reported from Kabul, and Laura Smith-Spark wrote in London.