EXCLUSIVE: The on-screen intensity of FX’s biker drama Sons Of Anarchy spilled behind the scenes yesterday. I’ve learned that SOA creator/executive producer Kurt Sutter got into a shouting match with co-star Tommy Flanagan on the set of the show. The altercation did not get physical and police were not called in as one source suggested. “Very hard day in Charming,” Sutter wrote cryptically on Twitter last night. “It’s my job to be the adult in the room. Unfortunately, today that adult was my father. Al was an angry man.”

This is not the first time sparks have flown on SOA whose dark and intense subject matter often has emotions running high behind the scenes. Last year, Sutter had a heated argument with series star Charlie Hunnam, which led to the actor’s scrapping SOA‘s panel at the summer TCA press tour. The two patched things up after a joint meeting with FX boss John Landgraf. Things on the show seemed to be back to normal again after yesterday’s incident. Sutter is back on the set as SOA is wrapping production on episode 12 of its its current fifth season. On Monday, filming of the season finale is slated to begin with Sutter directing.

The finale will cap what is shaping up to be SOA‘s strongest season yet. This week, the biker drama drew 4.6 million viewers and a 2.4 rating in adults at 10 PM on Wednesday, up 14% from last week. It was the No.1 program in all of television at 10 PM, beating all-original competition on the broadcast networks for the first time.