The United Nations on Wednesday raised concern for the safety of stateless Rohingya Muslims seeking asylum in Sri Lanka after Buddhist monks and hardline nationalists forced them to flee a UN shelter in the capital Colombo.

According to Reuters, in Tuesday’s incident, the Sri Lankan monks and nationalists stoned the shelter, prompting its 31 Rohingya occupants – mainly women and children – to flee for their own safety, witnesses said. No injuries were reported.

In a statement, the UN High Commissioner for Refugees said the incident was alarming, saying the refugees had been victims of violence and persecution in Myanmar, from which some 422,000 Rohingya have fled to nearby Bangladesh over the past month.

“UNHCR emphasizes that (the) refugees … need international protection and assistance. UNHCR urges the public and all those concerned with refugees to continue extending protection and to show empathy for civilians fleeing persecution and violence.”

It said the Rohingya had been staying in Buddhist-majority Sri Lanka with the Colombo government’s approval and UNHCR was providing assistance “until longer-term solutions can be found”.

President Maithripala Sirisena’s government condemned the attack on the refugees as “shameful” and urged police to hunt down the perpetrators.

The Rohingya group fled Myanmar in 2012 and lived in India as refugees for nearly five years before trying to migrate illegally to Sri Lanka, a lawyer representing them told Reuters.

There has been an exodus of Rohingya from Myanmar’s Rakhine state since Aug. 25, when attacks by Rohingya militants triggered a military crackdown that the United Nations has branded “ethnic cleansing”.