More than 500 Rohingya refugees escaped from detention in Malaysia on Wednesday following a protest but most were rearrested, immigration officials said.

The Immigration Department said 528 Rohingya fled after breaking a door and barrier grill at a temporary detention center in northern Penang state. Police and other agencies were deployed and rearrested 362 detainees, the department said in a statement.

“The search for the remaining detainees is continuing,” it said, without giving details on what sparked the breakout.

Penang police chief Mohamad Shuhaily Mohamad Zain told local media that six detainees were killed by a passing car while trying to cross a highway. He said the victims were two men, two women, a boy and a girl.

He was quoted by the national Bernama news agency as saying that police had set up roadblocks to hunt for the remaining detainees, who included 28 women and 12 boys. He said the detainees were barefooted and were likely to be weak and tired.

Malaysia, which has a dominant Muslim population, is a preferred destination for Muslim Rohingya fleeing from Buddhist-majority Myanmar or those seeking to escape misery in refugee camps in Bangladesh.

Malaysia doesn’t grant refugee status, but it houses about 180,000 refugees and asylum seekers accredited with the U.N. refugee agency, including more than 100,000 Rohingya and other Myanmar ethnic groups. Thousands more stay undocumented after arriving in the country illegally by sea.