Actor Scott Caan was flown back to LA from the set of the highly-anticipated “Hawaii Five-0” TV show last week with a serious knee injury, sources confirmed.

It appears he hurt himself while filming a stunt for the action show.

Caan, 33, immediately underwent surgery for what is believed to be a torn ACL, sources familiar with the situation told The Post.

The operation was conducted as an outpatient procedure, sources said.

Though it appears shooting schedules had to be rearranged, production on the CBS series, a remake of the hugely popular ’60s show, continued without Caan, who plays “Danno” Williams, the No. 2 man to Detective Steve McGarrett.

“Yes, his injury will be noted in the story line,” a spokesperson for CBS told The Post. “Partnering with someone like Steve McGarett, you’re bound to get a few bumps and bruises.”

The show says it has no plans to slow down filming to wait for Caan’s return — perhaps as soon as this week.

Alex O’Loughlin, who plays McGarrett, has said that filming on the series has been especially rough.

“I’ve been getting thrown out of tanks, beaten around the island of Oahu,” O’Loughlin told celebrity Web site HollywoodNews.com.

Caan, a gym rat and avid surfer, has had knee trouble in the past, but not to this extent, according to sources.

Filming on the series, which is being produced completely in Hawaii, began only a few weeks ago, according to sources at CBS.

“Hawaii Five-O” is perhaps the fall’s most anticipated new show — not the least because it is based on one of TV’s best-known cop shows.

Although billed as a revamp of the original series, several fan favorites — including the theme song and McGarrett’s famed one-liner “Book ’em Danno” — are expected to make a return.

Caan says he’s never seen the original.

“I’ve made a point not to see [the old series], because I want to keep it fresh and not have any old ideas,” Caan told TV Guide.