(Associated Press)

The Cowboys and Raiders got together for the first of two joint practices Tuesday at Dallas’s training-camp site in Oxnard, Calif., which is northwest of Los Angeles. Lots of Raiders fans were there. It went poorly.

Here’s Lindsay H. Jones of USA Today:

Stern warning from both coaching staffs, extra police officers, many of them wearing flak jackets, police dogs and the decision to separate Cowboys and Raiders fans to opposite sides of the training facility couldn’t prevent a melee in the first of two joint practices Tuesday afternoon.

A brawl between the Raiders offense and Cowboys defense – started after a hard tackle by Dallas cornerback Morris Claiborne – spilled over the sideline and up against the fence where a large group of Raiders fans were watching.

That’s when it got ugly.

Dallas cornerback B.W. Webb said he felt someone on his back, swinging a helmet at his head. Thinking it was a player, Webb spun around and swung his right arm. Webb told USA TODAY Sports he didn’t know it was a fan. Many of the Raiders fans brought helmets to get autographed by players after the practice.

Jones reports that police stationed themselves between the sideline and the Raiders fan section after the brawl. No one was hurt, and Cowboys owner Jerry Jones and Oakland owner Mark Davis were jovial at a joint post-brawl news conference.

The Cowboys’ Twitter feed joined in the celebration of the melee.