The attackers issued no demands but went on a rampage, killing at least eight recruits and instructors. One attacker was killed in the siege that followed and, in a gory finale, three detonated suicide belts, killing themselves. More than 100 people were wounded.

Image Pakistani paramilitary soldiers arresting one of the gunmen. Credit... Rahat Dar/European Pressphoto Agency

“They were barbaric,” a senior trainer at the center said. “They had no demands. We didn’t understand what they wanted. They just kept killing.”

The strike was aimed at killing and terrorizing future law enforcers and demonstrated once again the militants’ ability to reach deep into the Pakistani heartland.

Pakistan, a nuclear-armed state, has been mired in political wrangling since an election last year, with leaders fighting each other instead of joining efforts against the insurgency, which is slowly strangling the country. The government’s impotence will greatly complicate the Obama administration’s efforts to bring order to Afghanistan, whose militants slip through Pakistan’s porous borders.

Rehman Malik, a senior adviser in Pakistan’s Interior Ministry, said there were seven assailants. Three were arrested, he said, and four died in the siege. They rented an apartment in Lahore but came from Pakistan’s lawless tribal areas in the west, he said.