Ethiopia’s Prime Minister Abiy Ahmed showed no sign on Thursday of halting a military campaign in the Tigray region, despite international pressure to avert civil war with a powerful ethnic faction. A humanitarian source said shelling and shooting had been heard in the region since the early hours of Thursday, and nearly two dozen soldiers had been treated at a clinic near the border with the Amhara region. The source did not say which side of the conflict the injured troops were drawn from. Federal troops and regional forces clashed in the northern region on Wednesday, after Abiy ordered them to respond to an alleged attack on government forces in the region by the Tigray People’s Liberation Front (TPLF). The TPLF was the dominant political force in Ethiopia’s multi-ethnic ruling coalition for decades, but quit after Abiy, a member of the Oromo ethnic group, took office two years ago and reorganized the coalition into a single party. Countries in the region fear that the crisis could escalate into all-out war under Abiy, who won the 2019 Nobel Peace Prize for ending a decades-old conflict with neighboring Eritrea but has had to contend with outbreaks of ethnic unrest.