Construction was set to begin this week on a giant telescope on the barren summit of Mauna Kea, a volcano on Hawaii’s Big Island, considered the best observatory site in the Northern Hemisphere.

The project, however, has long drawn the opposition of those who say it would desecrate the mountain’s sacred ground.

On Wednesday, that opposition had a new face: About 30 Hawaiian elders were arrested as they blocked a road leading to Mauna Kea’s summit to halt the construction, organizers said. They described an emotional but peaceful scene as the elders, who were sitting under tents on the road, were escorted by police officers to nearby white vans while dozens of other protesters chanted and cried. Some had to be carried.

“We have come to the point in time where enough is enough,” Leilani Kaapuni, one of the elders, said in a phone interview. She said she was arrested for obstruction of a government road but later returned to the blockade. “This mountain is sacred,” she said.