Several thousand protesters took to the streets in Ethiopian cities this week, demanding Prime Minister Abiy Ahmed do more to tackle simmering ethnic violence following the kidnapping of a group of university students.

Armed men abducted the students from Dembi Dollo University in the Oromiya region in early December, according to survivors who escaped. The government said earlier this week that the army had rescued 21 of the students, but at least 12 others are still missing.

While the kidnappers’ identity or motive is not clear, the incident has revived widespread fears about ethnic violence ahead of this year’s election and intensified pressure on Nobel Peace Laureate Abiy, who comes from the Oromo ethnic group.

Many of the students were Amhara, a group that has clashed with Oromos in the past.

In the past six months, clashes on campus have killed 12 students and played a role in the decision of 35,000 to drop out of university, according to the higher education ministry.

Anger about the kidnapping has focused on Abiy, who won the Nobel Peace Prize last year for signing a peace deal with former enemy Eritrea and has overseen political reforms since coming to power in 2018.

He has been unable, however, to stamp out ethnic violence in Africa’s second-most populous nation, including among his Oromo group.

Families of the missing students met the prime minister and other senior government officials on Thursday, receiving assurances that their relatives were safe but no further information about their whereabouts or any plans to rescue them.

“We were just told by the officials that they are alive,” said Yeneneh Adugna, a local priest and a farmer from Gondar, whose 23-year-old daughter Germanesh Yeneneh, a third-year biotechnology student, is missing.

“The last phone call conversation I had with her was two weeks after her abduction,” Yeneneh said. “She told me not to worry.”

Several thousand people took part in marches in a handful of cities during the week to demand their release and activists made #BringBackOurStudents trend online.

Another protest is planned in Gondor, the capital of Amhara, on Sunday, the families said.

Belay Abebe, father to a second-year journalism student, said his daughter had also called him after she was abducted and said she was safe.

“We ... demanded to talk to the students over the phone,” another relative of one of the students told Reuters, asking for anonymity for fear of possible reprisals. “There was no willingness from the officials to let us speak with the students.”

Endeshaw Tasew, general commissioner of the federal police, said on Wednesday that the government knows where the students are but declined to give further details.