Santa Monica, Calif. ? Rock musician Tommy Lee testified Tuesday at the start of a civil trial over the drowning of a 4-year-old boy in his pool, saying all the children at his son’s birthday party came with adults who should have been watching them.

“If they were alone, it would be my problem. They weren’t,” said the former drummer for the band Motley Crue. He added that he kept an eye on his own two children at all times during the June 16, 2001, party during which Daniel Karven-Veres drowned.

Daniel’s parents, actress Ursula Karven and TV producer James Veres, are seeking unspecified damages in a wrongful-death lawsuit against Lee, 40.

Attorney Thomas Girardi, who represents Daniel’s parents, said in his opening statement that his clients had been unaware that their child would be swimming. There was one life jacket, and Lee gave it to his own son, Brandon, Girardi said.

Girardi said Lee planned the party at his Malibu home at the last minute because his estranged wife, actress Pamela Anderson, had a party for Brandon the week before.

“Mr. Lee decided to throw a party, too,” Girardi said. “But this was a party for his pals. The pictures show guys with tattoos.”

Lee’s attorney James Baratta countered that the party was carefully planned, that Lee arranged for a magician, a petting zoo and a Buzz Lightyear character to entertain the 15 to 20 children.

Girardi said Daniel’s parents sent him to the party with a male caretaker, an exchange student from Germany. The tragedy occurred after the caretaker decided to leave the party and entrusted Daniel to another family’s nanny, both lawyers said.

The German caregiver has disappeared and will not be a witness, they said.