WASHINGTON -- Bud Norris kept his cool after allowing two early runs, and the resurgent right-hander was rewarded by some unlikely power sources.

Humberto Quintero and Geoff Blum each homered in a seven-run fifth inning, Norris won for the seventh time in eight decisions and the Houston Astros beat the mistake-prone Washington Nationals 8-2 Monday night.

Norris (9-8) allowed two runs and six hits in 6 2/3 innings. The right-hander walked four and struck out six. The Astros are 10-1 in Norris' previous 11 starts. He is 7-1 with a 3.52 ERA over that span.

"Earlier in the year, [Norris] wasn't able to stop the inning right there with two runs," said Astros manager Brad Mills. "Sometimes they'd put up three and four, and that's tough to come back [from]. Tonight, he was able to stop it right there and then put up six more real good solid innings."

Houston has won six of eight and is 12-6 in September. Washington lost its fourth straight.

The Nationals committed three errors leading to four unearned runs in the fifth, when the Astros erased Washington's 2-1 lead with their highest-scoring inning of the season.

"It was just a bad inning, a terrible inning," Washington manager Jim Riggleman said.

And the Astros happily exploited Washington's generosity.

"Good teams take advantage of mistakes, and they made a few for us," Blum said.

Quintero's two-run homer, his fourth, and Blum's three-run drive, his second, both came off Livan Hernandez (10-12).

"Quintero isn't necessarily really known as a power threat, but he really got into one pitch tonight, and Blum came in a big spot and hit a three-run homer," Norris said. "You're not going to get a lot of seven-run innings, but when you do you're not going to complain."

The game drew 10,999, the smallest crowd in Washington, D.C., since the Montreal Expos relocated before the 2005 season.

"It would be tough for me as a fan to come watch us when we're playing bad," said the Nationals' Adam Dunn.

Dunn's two-run double put Washington ahead in the first. Adam Kennedy drew a one-out walk and Ryan Zimmerman singled before Dunn pulled a double into the right-field corner.

A safety squeeze by Norris cut the lead in half in the third. Brian Bogusevic led off with a double for Houston's first hit, took third on Quintero's single to right and raced home when Norris dropped a bunt down the first-base line.

Houston rallied in the fifth.

Chris Johnson led off with a double, moved to third on what was scored an infield hit by Bogusevic and scored when first baseman Dunn's shovel toss wasn't cleanly handled by Hernandez. Quintero followed with a two-run homer and Norris' fly ball to left was misplayed by Willie Harris for a two-base error.

Following Jason Bourgeois' strikeout, Jeff Keppinger singled, but center fielder Roger Bernadina muffed the pickup, allowing Norris to score.

"Those are errors we cannot make," said Harris. "Those are stupid errors."

After Hunter Pence flied out, Blum lofted a three-run homer down the right-field line.

Hernandez worked five innings, yielding eight runs -- four earned -- on eight hits. He walked none and struck out five.

Game notes
Hernandez has thrown a team-high 199 innings this season. He has nine 200-inning seasons in his 15-year career. ... Houston's Michael Bourn sat out with a strained right ribcage muscle sustained Sunday. ... LHP Ross Detwiler, who has worked out of the bullpen since returning from a stint on the disabled list following right hip surgery, will make his first start of the season Thursday in the series finale against the Astros. ... Astros LHP Tim Byrdak struck out the only batter he faced -- Dunn with the bases loaded -- to end the seventh. Byrdak has not pitched more than 1/3 of an inning in his last six appearances and 11 of his past 12. He has been scored on once in 42 outings dating to June 12. ... Zimmerman had two hits, his team-high 46th multiple-hit game of the season. ... Houston's last seven-run inning came versus Florida on Aug. 12, 2009.