James Shaw, New Zealand’s climate change minister and Green Party co-leader, was punched in the face while on his way to parliament Thursday.

Police said a 47-year-old man has been arrested and is due to appear in court Friday. It is not yet known why the attacker punched Shaw, although New Zealand Trade Minister David Parker told local media that Shaw had told him the attacker “was shouting things out about the United Nations.”

The United Nations Environment Assembly is currently underway in Nairobi. On Wednesday, the United Nations released a report that said drastic action needed to be taken to avoid millions potentially dying prematurely of air and water pollution by 2050.

Shaw’s injuries were not serious, but he went to the hospital as a precaution. “He’s feeling a bit tender and a bit shaken up,” said his press secretary, Peter Stevens.

Politicians are known to mingle with the public in New Zealand, and the assault appears to have shaken the political leadership.

“In New Zealand, you just don’t expect these things to happen,” said Prime Minister Jacinda Ardern, the only New Zealand lawmaker consistently accompanied by security.

“We have an environment in New Zealand where politicians are accessible, and that’s something we should feel proud of. We are, after all, here to serve people. But today’s events really show we cannot take that for granted,” Ardern said.

Shaw told New Zealand media outlet Stuff that the injury “looks worse than it is.”