SAN FRANCISCO -- The San Francisco Giants took advantage of a San Diego fielding error to score three runs in the first inning and continued to pound out hits in a 13-9 win over the Padres on Wednesday.

With the win, the Giants completed a sweep of the three-game series with the Padres.

Brandon Belt was 3-for-4 with five RBIs and fell a home run shy of the cycle, and Hunter Pence went 3-for-3 with two RBIs and two runs scored.

"With him he kids all the time before the game, 'a good day for the cycle' but we're still waiting on it," Giants manager Bruce Bochy said of Belt. "He had a shot at it but he did a nice job getting the runs in, using the whole field. He just missed one the first time up, but throughout the lineup, guys did good things and found ways to get those runners in."

On his success at the plate, Belt said, "One of the reasons I've had some success against the shift is because I don't think about it. I stick with my approach and wait for something good to hit. Something I can hit hard."

Jeff Samardzija (3-1) was the winning pitcher, allowing five hits and five runs with seven strikeouts in 5 2/3 innings.

"Ending the homestand on a win is always important, and the way we did it there with a sweep was nice, and what Johnny (Cueto) did last night (seven-hit shutout) was unbelievable and really set us up today to go out and have all our guns ready to approach this game how we needed to."

The Padres had nine hits, including home runs from Matt Kemp, Wil Myers and Adam Rosales, but they were still outscored 19-13 in the series.

"It's tough, it's the way baseball goes sometimes," Myers said. "You have your ups and downs. Every team, whether it's a first-place team or a last-place team, every team goes through their ups and downs. It just so happens we went through a whole series with a lot of downs, but we've got to bounce back and have a good series in L.A."

San Diego starter Andrew Cashner (1-2) lasted just 2 2/3 innings, giving up six hits and four runs.

"I never got in a rhythm," Cashner said. "I didn't locate very well and anytime your offense puts up nine runs you have to be more efficient on the mound -- starters, everybody. Too many free passes, but, I mean, overall, I didn't command my fastball today."

In the first inning, Denard Span reached base on a popup that Padres third baseman Brett Wallace failed to catch as the ball bounced off the heel of his glove. Joe Panik followed with a walk. With runners at first and second, Matt Duffy singled to right, loading the bases.

Belt and Brandon Crawford each followed with sacrifice flies and Pence capped the inning with an RBI triple to right, scoring Duffy.

The Padres took the lead in the third, scoring four runs to end a 12-inning drought.

Alexei Ramirez singled to right and scored on a booming triple by Jemile Weeks off the wall in right-center. Cashner grounded to short, but Crawford played the ball at his usual position, and that allowed Weeks to score as Crawford threw out Cashner at first. Kemp capped the inning with a two-run homer.

But the Giants went back in front in the bottom of the third by scoring three runs, with Samardzija's two-run single being the big blow. The Giants added four in the fourth to make it 10-4. The Giants kept expanding their lead with an assortment of singles, doubles and triples.

"I think that's a testament to our offense," Duffy said. "We have the ability to hit a couple of homers but if not we can hit a team to death, so I feel like we were able to do that today. Someone pointed out in the eighth inning we hadn't hit a home run and that's all right obviously so it was definitely a big day for us."

The Padres scored in the sixth on a double to right-center by Wallace.

Myers hit a three-run homer to left in the seventh to cut the deficit to 13-8.

NOTES: The Padres are 3-6 in their last nine games. ... RHP Andrew Cashner's 2 2/3 innings was the fourth shortest start of his career. He is 0-3 with a 7.40 ERA in his last five starts against the Giants. ... Giants RHP Jeff Samardzija leads all pitchers in the majors with five RBIs in his first five starts this year. His previous career high in a season for RBIs was three in 2014 and 2012. ... The Giants have won 11 of their past 14 games against the Padres, including eight in a row at home. ... The Giants have hit only five home runs in their last 13 games (6-7 record). ... The Giants' 16 hits on Wednesday are one short of their season high of 17 vs. Dodgers on April 7. San Francisco has 11 triples on the season, tied with Arizona for the most in the majors.