Signs are posted outside Camp Migizi, a small encampment of mostly indigenous water and land protectors located right beside the Enbridge Line 3 construction site on the Fond Du Lac Native American reservation in Cloquet, MN. (Alex Kormann, Star Tribune/The Minnesota Star Tribune)

DULUTH – The Fond du Lac Band of Lake Superior Chippewa is telling pipeline protesters who are not band members to respect its sovereignty after a "potential explosive device" prompted an evacuation near an Enbridge pipeline work site on the band's reservation Friday.

The band's governing body said in a statement that it recognizes that some people oppose its decision to allow the project within its borders but asked protesters to honor its sovereign authority.

A half-mile area around a rural stretch of Ditchbank Road near Cloquet was evacuated for several hours following reports of a package being thrown onto a work site as protesters were dispersing Friday afternoon, according to the Carlton County Sheriff's Office. A bomb squad was called to the site, and state and federal authorities are investigating.

"After careful examination, it was determined that the device was not an explosive agent," the Sheriff's Office said in a news release. "Investigators are following up on a number of leads."

Forty area residents were evacuated in addition to pipeline workers in an incident the Fond du Lac Band said "created widespread public safety concerns." Emergency alerts were initially send to a large number of northeastern Minnesota residents before another alert clarified the evacuation order affected only residents in the area.

Enbridge also briefly shut down its pipelines in the area.

The company said two "nonexplosive items" were removed from inside an open pipe.

"This incident disrupted not just a pipeline and the delivery of energy, but the lives of real people," Enbridge said in a statement. "This is unacceptable and we will seek to prosecute those involved to the full extent of the law."

Protest group Camp Migizi said in a statement: "The claim that protesters would undertake such an activity is false and yet another attempt by Enbridge to divide the community over Line 3 resistance. We stand by water protectors who act peacefully to protect our land, water and stand up for Indigenous rights."

A number of protesters have been arrested in recent weeks after locking themselves to equipment, climbing inside pipes or otherwise blocking work on the 337-mile pipeline they say will increase the risk of oil spills in pristine areas and exacerbate climate change. The project stretches across about 13 miles of land owned by the Fond du Lac Band of Lake Superior Chippewa, under an agreement between the band and the Canadian pipeline company.

Enbridge says the project, which travels a total of 1,031 miles between Alberta and a terminal in Superior, Wis., replaces an aging pipeline and will increase safety.

Authorities are asking for help locating those suspected of throwing the suspicious package onto the work site. A 2013 silver Toyota sedan with Virginia license plates was identified as the "suspect vehicle," the Sheriff's Office said.

"We will push for the maximum charging and penalties for everyone involved in these types of crimes," Sheriff Kelly Lake said in a statement.

Brooks Johnson • 218-491-6496