SEATTLE -- A stomach bug swept through the Seattle clubhouse Thursday afternoon, leaving the Mariners' lineup without third baseman Kyle Seager for the first time this season and with a less-than-full-strength Nelson Cruz.

After the way San Francisco starter Ryan Vogelsong pitched in a 7-0 Giants win, the Mariners were feeling even sicker.

Vogelsong threw 6 2/3 innings as part of Seattle's fourth shutout loss in its past eight games. The Giants took advantage of a Mariners defensive miscue to score three early runs, then piled up four more runs in the eighth.

San Francisco had 10 hits and went 6-for-10 with runners in scoring position.

"A pretty good recipe for success," said Giants rookie catcher Andrew Susac, who went 2-for-4 with an RBI.

Vogelsong (5-5) allowed only three hits in his best outing of June, and then the Giants' bullpen held on against a depleted Seattle lineup. Javier Lopez, Hunter Strickland and Jeremy Affeldt completed the shutout.

"I was able to get going tonight and make some pitches," Vogelsong said.

The Mariners got a two-out single in the first inning, then they didn't get another hit until the seventh. Seattle (30-37) finished with five hits while getting shut out for the seventh time this season.

Seattle scratched Seager and All-Star second baseman Robinson Cano (back spasms) an hour before first pitch, and manager Lloyd McClendon questioned his own decision to play Cruz.

"He was throwing up right before the game, and he toughed it out," McClendon said after moving Cruz from right field to designated hitter in the 11th hour.

San Francisco (36-32) jumped out to a 3-0 lead with a three-run second inning, scoring all of the runs after Seattle shortstop Brad Miller dropped the ball trying to complete a double-play throw to first.

"It's always nice to have some points on the board," Vogelsong said. "It gives you a chance to attack the (strike) zone and do some things you might not normally do. It makes a big difference."

Right fielder Justin Maxwell, center fielder Angel Pagan and Susac had two hits each for the Giants, while third baseman Matt Duffy had a two-run triple in the eighth.

Mariners starter Mike Montgomery (1-2) survived a rough second inning to make it through 7 1/3 innings. He allowed seven hits, two walks and four runs.

"He settled down after that shaky second inning and really gave us some quality innings," McClendon said.

Vogelsong entered the game with an 0-3 record and 6.61 ERA in the month of June.

"It was a big outing for us," Giants manager Bruce Bochy said of Vogelsong's work Thursday. "He was really, really good."

Four hits, a walk and a botched relay on a would-be double play led to the game's first three runs.

After three consecutive batters reached to load the bases with one out in the second, shortstop Joaquin Arias, left fielder Nori Aoki and second baseman Joe Panik drove in runs on consecutive at-bats to give San Francisco a 3-0 lead.

The damage could have been minimized. Miller tagged second base on an Arias grounder, then tried to throw to first for the third out but ended up dropping the ball to allow the first run to score. Two more runs followed, with all three runs in the inning being earned.

"It's the human-element part of the game," McClendon said. "(Miller) just dropped it."

Montgomery, who was making his fourth career start, hadn't allowed more than two runs in any of his first three outings. He topped that figure in the second inning Thursday.

McClendon said he hopes to have Cano and Seager back in the lineup Friday.

NOTES: 3B Kyle Seager, who had the second-longest active streak in baseball at 192 consecutive games played, was a late scratch because of what the Mariners called food poisoning. Willie Bloomquist replaced him in the lineup. ... Mariners 2B Robinson Cano (stiff lower back) also was a late scratch. Cano's absence meant OF Dustin Ackley started at second base for the first time since Sept. 21, 2013. ... After Thursday's win, the Giants are 6-18 over their past 24 interleague games played at an American League park. ... The Giants have not set their rotation beyond this weekend's three-game series with the Dodgers, but it is possible that RHP Chris Heston could be headed back to Triple-A or the bullpen sometime after his Friday start. RHPs Jake Peavy and Matt Cain are close to coming off the disabled list.