GLENDALE, Ariz. -- It's early, but it's looking as though the Arizona Cardinals are on the verge of dominating the NFC West. They certainly dominated the San Francisco 49ers and quarterback Colin Kaepernick on Sunday at University of Phoenix Stadium.

The Cardinals intercepted Kaepernick four times, returning two of the picks for first-quarter touchdowns as they improved to 3-0 with a 47-7 rout of the 49ers.

Coming off a 48-23 victory at Chicago, the Cardinals are averaging an NFL-high 42 points per game.

With the victory, Arizona has a two-game lead over the rest of the NFC West. San Francisco, St. Louis and Seattle all stand at 1-2 after three games.

"I thought we came out with a purpose," Cardinals coach Bruce Arians said. "We played for 60 minutes with that purpose and that was to get into first place in our division."

The 49ers (1-2) couldn't get anything mounted offensively against Arizona's aggressive defense. With less than five minutes remaining, Kaepernick had completed only one more pass (five) than he had intercepted. And he had only thrown for 33 yards.

He finished 9 of 19 for 67 yards along with his four picks. Kaepernick ran for 46 yards and scored the 49ers' only touchdown, tucking the ball and running for a 12-yard score.

"No. Never crossed my mind," Kaepernick said when asked if he could have foreseen his type of performance. "Very hard to deal with. Very hard to see myself go out and play like that and hurt this team the way I did.

"I nullified all the efforts of every other player on that field today and that's something I have to fix. I have to be better for this team moving forward."

The Cardinals might have shut out the 49ers had punter Drew Butler not made a poor kick that was returned 37 yards by former rugby star Jarryd Hayne. That return helped set up Kaepernick's touchdown run.

Cardinals quarterback Carson Palmer was 20 of 32 for 311 yards with two touchdowns -- both to Larry Fitzgerald, who was named NFC Offensive Player of the Week after catching eight passes for 112 yards and three touchdowns last Sunday.

Against the 49ers, Fitzgerald caught nine passes for 134 yards and scores from of 4 and 8 yards.

Arizona backup quarterback Drew Stanton came on in relief of Palmer with 1:58 to play and closed out the game.

It was a mess that will require plenty of cleaning for the 49ers. The Cardinals intercepted Kaepernick twice in a span of 2:03 in the first quarter and returned both of them for touchdowns to a take a lead they never surrendered.

Cardinals cornerback Justin Bethel, getting his first defensives snap of the season, stepped in front of tight end Vernon Davis and rambled 21 yards into the end zone after snaring Kaepernick's first pass of the game.

His fourth attempt produced a similar result. Looking for veteran Anquan Boldin on a short curl route, safety Tyrann Mathieu read the play and stepped in front of Boldin, grabbing the pass and high-stepping his way 33 yards for another pick-six for the Cardinals.

"Going into this game, obviously the focus for them was to run the football," Mathieu said of the 49ers. "But their passing game has been simplified so much, it was easy for us to anticipate routes and just get some good breaks on the ball today."

Arizona now has scored 12 defensive touchdowns since the start of the 2013 season, the most in the NFL. The Dallas Cowboys and Kansas City Chiefs have the second most with eight defensive scores.

After the second pick-six, the 49ers ran the ball 13 consecutive times during their next three possessions. Asked if that was by design to protect the ball, 49ers coach Jim Tomsula said, "No. That was on me. I told our runs coach, 'Let's get that thing running a little bit. Let's calm things down."

Chris Johnson rushed 22 times for 110 yards and scored on touchdown runs of 6 yards and 1 yard during the second quarter as Arizona cruised to a 31-7 halftime lead.

The Cardinals also registered a safety in the game, tackling running back Carlos Hyde in the end zone during the fourth quarter to extend their lead to 40-7.

NOTES: The Cardinals honored former S Adrian Wilson at halftime by making him the 15th person to be inducted into the franchise's Ring of Honor. ... 49ers RB Reggie Bush did not travel with the team because of a nagging calf strain, which he suffered in a Week 1 victory over the Vikings. ... Bobby Massie, who missed the Cardinals' first two games of the season while serving a suspension for violating the league's substance-abuse policy, started at right tackle in place of Earl Watford. ... Cardinals S Rashad Johnson was fined $17,363 for his Week 2 hit on Bears QB Jay Cutler.