Economist, author, and George Mason University (GMU) professor Tyler Cowen was pepper sprayed in his classroom today by a man trying to place him under citizen's arrest. ArlNow.com reported on the incident, which took place at GMU's Arlington, Virginia, campus this afternoon.

Police say the man entered the classroom and attempted to place the professor under a citizen's arrest. The professor tried to get the man—described as a white male in his 20s or 30s—to leave, at which time the man pepper sprayed him and a scuffle ensued, according to Arlington County Police spokesman Dustin Sternbeck. The professor did not know the man, Sternbeck said.

The ArlNow.com account didn't identify the professor, but several commenters said it was Cowen.

Tom Roussey, a reporter with D.C.'s ABC7 news, then confirmed with GMU that it was Cowen who was pepper sprayed.

According to Roussey, the man entered Cowen's classroom this afternoon, jumped on a desk, said he was placing Cowen under citizen's arrest, and pepper sprayed Cowen in the face. Cowen ran, the intruder chased him, and students in the hallway caught the suspect and held him until the Arlington Police arrived and arrested him. The man wasn't a student, Arlington County police officers say, and charges are pending.

A few hours after the incident, at 6:35 p.m., Cowen tweeted:

Cowen and the dozen or so students in his classroom were affected by the pepper spray but not taken to the hospital. No word yet on what motivated the intruder.

Update: Here's an account from ABC7's broadcast last night, which ever-so-slightly expands on what Roussey was tweeting out earlier. It seems Cowen was teaching a class on vigilante justice at the time of the incident, and some students assumed at first that the intruder was part of the lecture.

Update 3/27: Cowen's attacker has been identified as a man named John Pendleton.