BILLINGS, Mont. (AP) - Two bison advocacy group members were arrested Wednesday after allegedly refusing to leave a portion of Highway 191 that had been closed to allow state and federal officials to haze bison back into Yellowstone National Park.

One of the two Buffalo Field Campaign members, Peter Bogusko, also is accused of kicking out a rear window of a patrol car after his arrest, Montana Highway Patrol Capt. Tom Butler said.

Bogusko pleaded not guilty Thursday to felony criminal endangerment and misdemeanor obstructing an officer, said Stephany Seay, a spokeswoman for the advocacy group.

He was taken to the Gallatin County jail after his arrest; efforts were being made Thursday afternoon to post a $3,000 bond set in the case, Seay said.

The other group member, Dan Brister, was cited with two misdemeanor counts of resisting arrest and obstructing an officer. He was not jailed.

Bogusko and Brister were arrested at about 2:30 p.m. Wednesday as the Montana Department of Livestock was pushing 300 to 400 bison back into the park. U.S. Forest Service officers had blocked traffic on a portion of Highway 191 north of West Yellowstone to allow the animals to cross.

Montana Highway Patrol Trooper Shane Cox was watching for traffic coming off side roads, and asked Bogusko and Brister to leave a closed portion of the highway as the bison were moving through, Butler said.

Butler said Cox was trying to ensure the safety of everyone at the scene and arrested the two men only after they refused to leave the closed area.

Cox reacted appropriately to their refusal to leave, Butler said.

"There are no easy answers here, especially when there's 300 buffalo coming at you," he said.

But Brister said group members were trying to shoot video of the hazing operation and Cox overreacted.

He said the incident started when group members voiced concern to Cox that vehicle traffic was still moving through the area where the bison were being pushed back toward the park.

"I think (Cox) is bringing too much attitude," Brister said.

Brister denied resisting arrest, and said the trooper threw him to the ground, causing a gash above his temple that required three staples to close.

Butler said Brister was "assisted to the ground, handcuffed and placed in the patrol car." He added that it was a tense, rapidly evolving situation in which several hundred bison were quickly approaching.

"I'll take my guy's word and see where it goes from here," Butler said.

Law officers drove Brister from West Yellowstone to Bozeman and back for medical treatment.

Butler said Thursday that the advocacy group and local law enforcement have had a good relationship for years, and he was "disturbed" and "completely disappointed" that the incident occurred.

He said he spoke with a leader of the advocacy group Thursday, and "both sides agreed to try to cooperate" in the future.