BOISE, Idaho (AP) – The first of two massive shipments of oil refinery equipment continued its trek along scenic U.S. 12 early Tuesday after being temporarily halted by members of the Nez Perce Tribe who blocked the highway in protest.

The load departed the Port of Wilma, near Clarkston, Wash., shortly before 11 p.m. Monday, The Lewiston Tribune reported. The two-lane highway in Idaho passes through the Nez Perce reservation and a federally designated Wild and Scenic River corridor.

Idaho issued a permit last week allowing Omega Morgan to begin hauling two giant water purification units, measuring 225 feet long, 21 feet wide and weighing 644,000 pounds, across the state, into Montana and on to the oil sands project in Alberta, Canada.

Nez Perce Chairman Silas Whitman said Monday night that collaboration and diplomacy have failed and tribal members anticipated “intercepting the loads at the reservation line.”

“We are tired of being pushed,” Whitman said at a news conference at the Clearwater River Casino.

Tribal leaders and other members stood their ground and stopped the load at about 12:40 a.m. Tuesday as loud shouting, drumming and whoops rang out, the Tribune reported.

Several Nez Perce Tribal Executive Committee members were removed by police, but within less than two hours, a barrier of police vehicles kept protesters away from the load as it moved eastward on the highway, the newspaper reported.

It was unclear if anyone was arrested. Earlier, interim Nez Perce Tribal Police Chief Daniel Taylor said if anyone blocks the road, police would have options that include asking people to leave the road, issuing citations or making arrests.

The latest megaload shipment had an Idaho permit to be on the highway between 10 p.m. Monday and 5:30 a.m. Tuesday. The Idaho Transportation Department issued a warning alerting northern Idaho motorists to expect delays.

Like previous megaload shipments that moved along the highway two years ago, the Omega Morgan trucks have angered environmentalists and leaders of the Nez Perce Tribe.

The latest batch of shipments is also being challenged by the U.S. Forest Service. On Monday, Nez Perce-Clearwater National Forest Supervisor Rick Brazell sent a letter to Omega Morgan executives objecting to the travel plan.

“The Forest Service does not consent, approve or otherwise authorize Omega Morgan to transport the subject over-legal loads on U.S. Highway 12” when it enters the forest boundary, according to the letter obtained by The Associated Press.

In the letter, Brazell states his agency still needs to complete a broader study on the potential impacts of megaloads before it can lend support to any specific shipment, and he claims the size and other aspects of the travel plan exceed newly developed guidelines, triggering an automatic review of a state-issued permit.

Brazell also accused the company of ignoring language in the state permit outlining Forest Service and Federal Highway Administration jurisdiction.

“We believe we are in full compliance with all applicable requirements, including notifying the appropriate federal officials,” Omega Morgan spokeswoman Olga Haley said in an email response to questions.

Earlier this year, a federal judge ruled that the Forest Service has authority to review megaload shipments when the trucks cross the forest boundary.

The ruling emerged from a lawsuit filed by environmentalists challenging a separate series of megaload shipments of oil refinery gear planned along the highway, which winds along the Clearwater and Lochsa rivers and through a mountainous and forested corridor protected by the 1968 Wild and Scenic Rivers Act.

In his decision, Judge B. Lynn Winmill made clear that the Forest Service had authority under a 1968 law to get involved in the state's decision to permit shipments, and he also found the Forest Service “acted unlawfully” by standing on the sidelines.

On Sunday, The Nez Perce Tribal Executive Committee passed a resolution opposing the shipments and urging the Forest Service to block them.