SAN FRANCISCO — The 49ers were wrapping up team drills at Candlestick Park on Sunday when a shaggy fan in nothing but shorts and shoes ran onto the field and approached coach Jim Harbaugh.

Harbaugh saw the fan coming and made eye contact with him when he got within a few yards. The fan fled to awaiting police officers on the sideline.

“Him and Harbaugh kind of had a moment,” left tackle Joe Staley said. “They locked eyes, and Harbaugh made him withdraw with his Chuck Norris eyes.”

“He called me ‘Coach,’ ‘Coach-something,’ ” Harbaugh said. “I didn’t say anything. I’m glad he was clothed, glad he wasn’t naked.”

The 49ers reported a crowd of 32,000 for their only public practice of training camp, although it appeared closer to 22,000 as no fans were allowed in the upper deck. About 8,200 showed for last year’s practice at Candlestick. Tight end Vernon Davis said, “I didn’t expect to see so many people here. To come out shows how much effort they’ll go to support us, and we greatly appreciate it.”

Tight end Delanie Walker injured his right knee early in practice and watched the remainder from a bench with his knee covered in ice. “I think we’ll dodge another bullet there,” Harbaugh said. Walker hurt the same knee in June when he banged linebacker Aldon Smith’s in practice, forcing Walker to miss some time in their mandatory minicamp.

Smith did not attend Sunday’s practice and “will be out for some time, maybe a week or so,” Harbaugh said. Smith suffered a bruised hip Friday night in the 49ers’ 17-6 exhibition victory over the Minnesota Vikings and drew the same “dodged-a-bullet” reference from Harbaugh after the game.