A suicide bomber dressed as a policeman blew himself up amid a gathering of high-ranking Afghan and NATO officials on Saturday, killing northern Afghanistan’s senior police official and wounding the top German commander in Afghanistan, among several other casualties, Afghan officials said.

The attack occurred during a security meeting in the governor’s office in the capital of Takhar province, a relatively peaceful part of the country. The officials had been discussing operations to prevent the spread of the Taliban across the north, particularly in neighboring Kunduz province, when a man opened fire and blew himself up, according to Afghan officials.

The blast killed at least four Afghans — including Gen. Daud Daud, the top police official in northern Afghanistan; the Takhar provincial police chief, Shah Jan Noori; and the governor’s secretary — and wounded at least 10 other people, including the provincial governor, Abdul Jabar Taqwa. The commander of German forces in Afghanistan, Maj. Gen. Markus Kneip, was also wounded, and two of his soldiers were killed, according to the German newspaper Der Spiegel.

The Taliban asserted responsibility for the attack, the latest in an apparent campaign to assassinate high-ranking military and government officials. Insurgents killed the Kandahar police chief last month inside his headquarters, and the governor of Kunduz was killed in a mosque bombing last October. Security in northern Afghanistan deteriorated sharply last year as insurgents spread from their traditional strongholds in the country’s south and east.

The violence again showed the Taliban’s ability to infiltrate supposedly secure government facilities to strike their targets. Last month, gunmen dressed as soldiers shot up the halls of the Defense Ministry in Kabul.

The Takhar governor was flown to Kabul for treatment after the attack, said Haji Mohammad Farid, the deputy governor. Afghan officials did not know the condition of the German commander.

Daud, the regional police commander who died, was formerly the deputy interior minister for counter-narcotics affairs. During the Soviet occupation, he had been an aide to guerrilla commander Ahmed Shah Massoud.

President Hamid Karzai denounced the attack as a “barbaric act of terror.”

In a separate development Saturday, Karzai instructed his defense minister to stop all night raids by NATO troops in Afghanistan and have only Afghan troops conduct such operations. The president’s decision, announced in a statement from his office, did not elaborate on how he intended to accomplish that goal.

The move follows years of criticism from Karzai about intrusive NATO military operations into Afghan homes, particularly those that harm civilians. But it appeared to be the most concrete step he has sought to reduce their frequency.

A spokesman for the U.S. military in Kabul, Maj. Sunset Belinsky, said NATO “fully supports President Karzai’s intent to have Afghan forces increasingly in the lead for operations.” But the coalition did not signal any intention of making radical changes soon.

Special correspondent Javed Hamdard contributed to this report.