KABUL, Afghanistan — Assailants armed with heavy weapons and suicide vests stormed the provincial prosecutor’s office on Thursday in one of the most peaceful cities in northern Afghanistan, battling security forces for more than six hours and leaving at least 10 people dead and dozens wounded.
The attack took place in Mazar-i-Sharif, the capital of Balkh Province, which has long been seen as a model of economic prosperity and stability. The Taliban claimed responsibility for the latest in a string of bloody assaults ahead of what is expected to be an intense fighting season.
Abdul Raziq Qaderi, the province’s acting police chief, said a preliminary assessment showed that the attack left 10 people dead and 60 wounded, civilians, lawyers and police officers among them. In the immediate aftermath of the attack, which ended at 6 p.m., officials were unable to identify the dead and wounded. The number of assailants remained unknown late Thursday, though the bodies of four attackers were recovered from the compound after the gun battle ended, Chief Qaderi said.
Witnesses’ accounts cited by local news media suggested that the militants wore Afghan security force uniforms. After killing the guards at the entrance, about 50 yards from the office of the provincial governor, the attackers fought their way inside the compound and took more than a dozen lawyers and visitors hostage.
Explosions and gunfire could be heard for more than six hours, as security forces tried to clear the area. The central hospital issued a plea for blood donations.
“There is smoke and the sound of rockets and machine gun,” said Dr. Muhammad Afzal Hadeed, a member of the Balkh provincial council, who was at the site. “The security forces went in thinking they had cleared the area, then they came under attack.”
The penetration of such a highly secure area raised concerns over what is expected to be the bloodiest fighting season in more than a decade of war. The Taliban typically escalate their attacks in the summer.
Mazar-i-Sharif, a bustling city presided over by the provincial governor, Atta Mohammad Noor, has been spared the bloodshed of most large cities across the country. Police officials often bragged not about the number of security forces they commanded, but about how few they needed to secure the city, one of Afghanistan’s largest and most prosperous.
Mr. Noor, a former mujahedeen fighter, oversaw the clearance operation in the offices of the provincial prosecutors, his office said in a statement.
Though there have been sporadic attacks on Mazar in the past, none appear to have been as deadly or prolonged as Thursday’s assault.
“These kind of attacks haven’t happened in Balkh in recent years,” Dr. Hadeed said. “It is worrying.”
Last year was the deadliest on record for Afghan forces and civilians, and almost everyone expects that grim trend line to continue, despite efforts to bring the Taliban to the negotiating table. This winter, the insurgency maintained an unusually intense fighting tempo, and the leadership has vowed to inflict even more violence through the course of the year. Coalition forces led by the United States military have stepped back entirely from day-to-day combat operations.
The roughly 13,000 remaining members of the international coalition, down from a peak of nearly 130,000, have been largely reduced to a training and support mission. That has left Afghan forces severely challenged, evidence of which emerged in a steady stream of attacks in the last week.
Those attacks include a bicycle bombing that on Thursday wounded 16 people in the southeastern city of Khost. Last week, another attack in Khost killed 17 people who had gathered outside of the offices of the provincial governor to demand his removal. Also in the last week, at least 13 people were wounded in two attacks in the capital of the northern province of Kunduz
