Police deny throwing concussion grenade at Dakota pipeline protester now facing possible amputation of her arm. https://t.co/UdhPehuu2W

— The Associated Press (@AP) November 22, 2016

BISMARCK, N.D. (AP) — A New York woman seriously hurt protesting the Dakota Access oil pipeline faces multiple surgeries and could lose an arm, her father said Tuesday, and protesters and law enforcement gave conflicting accounts about what might have caused the explosion that injured her.

Sophia Wilansky, 21, was listed in serious condition and was undergoing surgery at a Minneapolis hospital.

Wilansky’s father, Wayne Wilansky, said his daughter was hurt when law enforcement threw a grenade. The Morton County Sheriff’s Office maintains authorities did not use concussion grenades or any devices that produce a flash or bang during a clash late Sunday and early Monday near the camp along the pipeline route in southern North Dakota where protesters have gathered for months.

The sheriff’s office suggested in a statement Monday that an explosion heard during the skirmish might have been caused by small propane tanks that authorities said protesters had rigged to explode.

Dallas Goldtooth, a protest organizer with the Indigenous Environmental Network, did not immediately respond to a request for comment Tuesday. Wayne Wilansky disputed the claim by authorities, saying “there’s multiple witnesses and my daughter, who was completely conscious, said they threw a grenade right at her.”

The North Dakota Highway Patrol in a statement Tuesday backed up the sheriff’s office’s version of events, saying officers during the skirmish spotted protesters with “multiple silver cylinder objects.”

“It was at this time an explosion occurred and several protesters ran to the area, pulled a female from under the burned vehicle, and fled the scene,” the patrol said.

Officers who investigated found 1-pound propane tanks “including one that appeared to be intentionally punctured,” the agency statement said.