The cutting-edge but highly controversial Thirty Meter Telescope has been given the green light to proceed with construction, state officials announced today.

The announcement followed an early morning operation by state law enforcement officers to remove four unauthorized structures from the slopes of Mauna Kea, including two Native Hawaiian altars located in the mountain’s northern plateau, the planned site of the telescope.

“We expect that TMT construction will begin sometime this summer,” Gov. David Ige announced at a news conference at the state Capitol. “We will proceed in a way that respects the people, place and culture that make Hawaii unique.”

Those who oppose the billion-dollar-plus project immediately denounced the move.

“It’s a sad day in Hawaii,” Native Hawaiian activist Healalani Sonoda-Pale said. “If they’re going to move forward on this project, then we are going to have conflict up on the Mauna. There’s no question about it.”

Mauna Kea Hui leader Kealoha Pisciotta said about 20 state vehicles, law enforcement officers before dawn dismantled the religious structures, including ceremonial platforms for placing flowers, sacred water and other offerings during prayer.

The operation happened on the eve of solstice ceremonies, Pisciotta said.

“This state action is desecration, provocation (and) is a hostile and racist act committed against the Hawaiian people and the good people of Hawaii. This is Pono ole! (not righteous). Is this all for Astronomy?” she said.

At least one person reportedly was arrested on the mountain.

Pisciotta said police are blocking the road to the summit and are only allowing astronomers through, including Hawaiians who asked to go pray at the summit.

“They won’t let anyone up,” she said. “They said no. They may block us tonight, also.”

The Hawaii County Council issued a news release today saying that due to a “tremendous amount of calls and contacts” to its office, it has requested a report on the Mauna Kea operation, including the extent of involvement by the Hawaii County Police Department, Corporation Counsel and County Administration.

While project foes say the telescope will desecrate sacred land at the summit of Hawaii’s tallest mountain, scientists say the summit is one of the best places in the world for astronomy.

The new telescope is expected to allow astronomers to reach back 13 billion years to answer fundamental questions about the advent of the universe.

Henry Yang, Chairman of the TMT International Observatory Board of Governors, issued the following statement in response to today’s news:

“TMT is pleased and grateful that the notice to proceed has been issued by the Department of Land and Natural Resources to the University of Hawaii. We remain committed to being good stewards of Maunakea, and to honoring and respecting the culture and traditions of Hawaii. It has been a long process to get to this point. We are deeply grateful to our many friends and community supporters for their advice and for their encouragement and support of the TMT project over the years.”

Plans for the project date to 2009, when scientists selected Mauna Kea after a five-year, around-the-world campaign to find the ideal site.

The project won a series of approvals from Hawaii, including a permit to build on conservation land in 2011.

Protests disrupted a groundbreaking and Hawaiian blessing ceremony at the site in 2014. After that, the protests intensified.

Construction stopped in April 2015 after 31 protesters were arrested for blocking the work. A second attempt to restart construction a few months later ended with more arrests and crews retreating when they encountered large boulders in the road.

A group of universities in California and Canada makes up the telescope company, with partners from China, India and Japan. The instrument’s primary mirror would measure 98 feet in diameter. Compared with the largest existing visible-light telescope in the world, it would be three times as wide, with nine times more area.

Telescope parts have been built in California and partner countries while construction on Mauna Kea was halted.

The Associated Press contributed to this report.