The stars of "One Tree Hill" are going to make it a twosome.

Chad Michael Murray (search) announced Monday that he and his WB co-star Sophia Bush (search) are engaged to be married. Both performers are 22.

The actor, now promoting the romantic comedy "A Cinderella Story," made the revelation on CBS' "The Late Late Show With Craig Kilborn."

Murray said he popped the question while they were in Australia, where he was finishing work on the movie "House of Wax."

"I had like 500 candles ... and my assistant ... he had to light all the candles while I had to basically take her to a spa and keep her out of the house until the sun went down," Murray said. "I had a bunch of roses and I put lights down on a tennis court that spelled something out for her," he said.

Murray wouldn't specify what the message read.

"Dude, that's for her ... I'd love to tell you, but that's just for my girl."