SAN FRANCISCO >> The San Francisco 49ers might have attracted more fans to their practice Sunday afternoon at Candlestick Park than they did to their preseason opener 48 hours before.

Team officials estimated a crowd of 32,000 attended San Francisco’s Fan Fest, a five-hour event that concluded with a practice session on the team’s home field. The 69,732-seat stadium was less than half-full Friday night for the 49ers’ 17-6 victory over the Minnesota Vikings.

This was San Francisco’s only training camp practice that’s open to the public this year. The 49ers have always had a handful of summer practices open to fans in the past at their team complex in Santa Clara, but that is not logistically possible this year because of the ongoing construction of a new stadium being built adjacent to team headquarters.

Their current stadium worked just fine Sunday, as fans added energy and a lot of noise to the team’s 2½-hour practice.

Coach Jim Harbaugh said there were “four to five times more people than there were here last year” at the annual event. The atmosphere made for a crisp practice as the 49ers returned to training camp mode after a players’ day off Saturday.

“It was great interaction with the fans,” said Harbaugh, who signed autographs for almost an hour after practice ended. “I think it helped us being out here. There was a lot of support for our team and I think they felt that from the moment they stepped on the field. The players enjoyed that, it was really good for our team and we enjoyed that.”

The 49ers picked up in practice where they left off against the Vikings, with their offense continuing to show progress after struggling for long stretches during the first two weeks of summer camp.

The 49ers, who finished 26th in the NFL last year in total offense, drove 84 yards in 12 plays for a touchdown on their opening possession against the Vikings. That kind of production continued after the starters went to the bench as San Francisco out-gained Minnesota 412-208 in a game that was more lopsided than the final score.

San Francisco might have had it better against Minnesota’s defense than the 49ers have had it this summer against their own rugged defense in practice. That unit, which ranked fourth in the NFL last year and first against the run, often dominated the offense during team drills.

But quarterback Alex Smith moved the first-team offense down the field in a game-like situation Sunday, with the clock running, the scoreboard working and fans cheering loudly from the stands.

“The offense kind of beat up on us today,” safety Donte Whitner said. “They came to us like we’ve been going at them a little bit earlier in camp.”

The 49ers practiced without outside linebacker Aldon Smith, who led the team with 14 sacks last year as a rookie. Smith injured his right hip against the Vikings and is unlikely to practice during the upcoming week or play Saturday when the 49ers resume the exhibition season in Houston against the Texans.

Smith is the only new face in the starting lineup for a San Francisco defense that returns all 11 starters from last year. Parys Haralson, who started at right outside linebacker for the 49ers last year, took Smith’s place with the first team Sunday.

“Aldon will be out for some time, about a week or so,” Harbaugh said. “We’ll have to see how that goes.”

Harbaugh then turned back toward the stands to sign more autographs for the fans who lined barricades that stretched around the entire field. Fans were allowed on the field after practice ended, and thousands remained to mingle with players and coaches long afterward.

“You can tell that the fan base here is really into the San Francisco 49ers,” Whitner said.