Security was a major concern during Thursday night's Battle of the Bay between the San Francisco 49ers and Oakland Raiders. And it turned out for good reason.

Toward the end of the 49ers' 34-3 thrashing of their cross-bay rivals at Levi's Stadium, fists started to fly in the stands. Twenty people were arrested for public intoxication, including one for fighting, according to Santa Clara police. Another person was arrested for violating parole.

In one scuffle caught on video and posted on social media, fans of both teams can be seen throwing punches at each other. No injuries were reported.

Police said there were a number of arrests for other reasons.

"I think it would be unreasonable to bring 70,000 people together and there not be a single arrest," Capt. Wahid Kazem said.

Throughout the evening, a police helicopter hovered overhead and uniformed officers from a multiple agencies were visible all over the stadium in an effort to keep the peace.

Before the game, plenty of fans came together to mark the end of the longtime cross-bay rivalry as the Raiders prepare to move to Las Vegas. The last time fans were able to tailgate before their favorite teams played each other was in 2014 in Oakland.

"They had such a great time over there, and then we’re like, alright we have to have the same thing over here," said Marisa Hernandez of Stockton.