KABUL, Afghanistan – Two suicide bombers blew themselves up at an Afghan police headquarters Saturday, killing 12 officers in an area along the Pakistan border that still experiences heavy Taliban attacks even as NATO pours in more troops and resources.

The Taliban claimed responsibility for the attack in eastern Paktika province, which has long been a refuge for Islamist extremists from around the world. It is one of the most violent areas of Afghanistan, where NATO and Afghan forces fight daily against the Haqqani network, a Pakistan-based Taliban faction closely tied to al-Qaida.

The attackers, who were disguised in police uniforms, made it through three security gates, said Nawab Waziry, the head of Paktika’s provincial council. One attacker detonated his explosives inside the police headquarters building, while the other blew himself up near the entrance about 20 minutes later.

“The site was covered with blood,” Waziry said after visiting the scene. He said an intelligence report several weeks ago warned that suicide attackers wearing police uniforms would strike soon.

“Even with all this information, still police were not able to prevent this attack,” he said.

The blasts killed at least 12 officers, said Gen. Daud Andarabi, spokesman for the regional police commander in southeastern Afghanistan. Meyawer Khan, chief of criminal investigations for Paktika province, confirmed the death toll.

A NATO service member also was killed in a bomb attack in eastern Afghanistan on Saturday, but it was unclear if there was any connection to the Paktika bombing.

Although NATO has poured troops into the southern provinces of Kandahar and Helmand and has made progress in rolling back the Taliban, fighting has continued in the eastern provinces where the Haqqani network holds sway.

The area, about 92 miles south of Kabul, borders the Pakistani region of North Waziristan and has been the target of numerous U.S. drone strikes against the Taliban, al-Qaida and the forces of the Haqqani network.