A suspected air strike in Ethiopia’s Amhara region has killed at least 26 people, a hospital official says, as a state-appointed rights group detailed widespread killings of civilians since fighting broke out this month.

Last week, federal forces managed to push Fano militiamen out of most major towns in Amhara, but clashes have continued in other parts of the northern region, the Ethiopian Human Rights Commission (EHRC) said in a statement. The federal government declared a state of emergency on August 4.

The fighting, which has been fuelled by Fano accusations that the federal government is trying to weaken Amhara’s defences, is Ethiopia’s biggest security crisis since a two-year civil war in the neighbouring Tigray region ended in November.

Ethiopia’s government denies the allegations by Fano, an informal militia that backed federal forces during the Tigray war. Spokespeople for the government, the military and Prime Minister Abiy Ahmed did not respond to the Reuters news agency’s requests for comment on Monday about the suspected air strike or EHRC’s statement.

The suspected strike hit the town centre of Finote Selam on Sunday, said the hospital official, who asked not to be named for security reasons.

The official said on Monday that four people died at the hospital and another 22 either at the scene or on their way to hospital. Fifty-five people are being treated for injuries sustained in the explosion, the official said.

Tikikil Kumlachew, a university teacher who was visiting a relative in the hospital from an unrelated incident, said he had seen 14 bodies there and been told by a medical worker that another 12 had died.

“The explosion shook the city. I don’t know if it was a drone or something else. But it fell from the sky,” he said.

In its statement on Monday, the EHRC said it had received credible reports that strikes and shelling in Finote Selam and other towns had resulted in civilian casualties. It did not specify when these events had occurred.

EHRC’s statement said its investigators had documented a variety of incidents since the conflict started, including the killing of protesters who blocked roads, the looting of weapons and ammunition from police stations and prisons, and the targeting of Amhara regional administration officials.

In Amhara’s capital, Bahir Dar, civilians were killed on the streets or outside their houses, EHRC said, adding that there were credible reports of “many civilian casualties” in Gondar, the region’s second biggest city, and extrajudicial killings by security forces in Shewa Robit.

In Addis Ababa, Ethiopia’s capital, there have also been widespread arrests of civilians of ethnic Amhara origin, it said.