(CNN) -- A Comic-Con attendee stabbed another near the eye with a pen Saturday after they got into an argument over whether one was sitting too close to the other, police said.
The injured man, in his 20s, was taken to a hospital with a minor cut, said San Diego Police Officer David Stafford. The attacker, also in his 20s, was arrested and booked for assault with a deadly weapon, he said.
The incident took place in the San Diego Convention Center while fans were waiting for a panel featuring actor Seth Rogen discussing the science-fiction comedy "Paul."
"The room was very crowded and the males argued over one male sitting too close to the other," Stafford said.
The suspect was later seen being led away in handcuffs. He had on a blue "Harry Potter" T-shirt.
The panel was delayed for about 30 minutes while attendees were shown a series of movie trailers.
"Well, there is a crowd issue. It's gotten really crowded. And if anything, an incident like this points to the need for more space," convention-goer Zennie Abraham told iReport -- the CNN website that allows people to submit pictures and videos.
"Should Comic-Con be in San Diego? I think so, but San Diego's got to make more space for it. It's become too big and I didn't think anything like this could happen because it's a chill event but it did happen."
Comic-Con, the annual gathering of self-proclaimed fanboys and fangirls, began Thursday and concludes Sunday. Aside from the stabbing, the convention has proceeded without incident so far, Stafford said.