Air strikes in the northern Afghan province of Kunduz killed about a dozen civilians on Saturday, local officials said, as battle intensified there and in southern Helmand province.

The air strikes killed 13 civilians, said Safiullah Amiri, a member of Kunduz provincial council. The casualties included children, said fellow council member Amruddin, who pegged the civilian death toll at 12.

The bodies were brought into Kunduz city in the back of a truck as part of protests by dozens of civilians.

The civilian deaths occurred as Afghan and Taliban forces claimed to inflict heavy losses on each other in that province and in Helmand, two Taliban strongholds.

A spokeswoman for the NATO-led Resolute Support mission in Afghanistan did not respond immediately to questions on Sunday. Resolute Support, comprising troops from 39 countries, trains, advises and assists Afghan security forces.

The New York Times reported earlier that the air strikes that killed civilians followed a firefight between U.S. and Afghan soldiers that had been provoked by a Taliban working inside Afghan forces. Reuters has not confirmed the paper’s report.

Four Afghan soldiers died in the fight, a senior Afghan military source said.

A record number of Afghan civilians were killed last year as aerial attacks and suicide bombings increased, the United Nations said in a February report.

Kunduz is also where two U.S. soldiers were killed in combat on Friday. The U.S. Department of Defense identified the soldiers as Specialist Joseph Collette, 29, and Sgt. Will Lindsay, 33.

Fighting has accelerated during a period of recurring peace talks. The latest negotiating round concluded this month with U.S. and Taliban officials citing progress toward ending the 17-year war.

Afghan forces, with NATO air support, killed 58 Taliban, including several commanders, in Kunduz, the defense ministry said on Saturday via Twitter. The Taliban said that it had killed 19 members of Afghan forces and five from foreign forces.

Fighting was also fierce in Helmand, including more civilian deaths.

The Taliban on Saturday claimed an attack at a stadium celebration of Farmers Day in Helmand, which killed four people and wounded 31, including minor injuries to the province’s governor.

A day earlier, Taliban attacked two Afghan outposts in Sangin, killing 48 Afghan security personnel, said Hashim Alokozay, a Helmand member of parliament. Taliban spokesman Qari Yousuf Ahmadi said the two outposts were over-run, killing 52 Afghan troops and wounding 11 more.

Omar Zwak, spokesman for Helmand’s governor, said the Taliban also suffered heavy casualties.