Cameron Diaz's ex-boyfriends Justin Timberlake and John Mayer were in attendance Sunday as her family held a memorial service for her late father.

Emilio Diaz, 58, died of pneumonia Tuesday morning. On Wednesday, Cameron, 35, thanked everyone for their condolences in a message that read: "His humor and spirit will always live on in our hearts."

Guests arrived at the memorial service at Mahe in Seal Beach in non-traditional garb, People magazine reported.

"Most people started arriving at 1:30 and hardly no one wore black," a source told the magazine. "Lots of people were wearing Hawaiian shirts. It looked more like a party."

Timberlake and Mayer arrived separately and stayed until most people started leaving around 4 p.m. — after Cameron had spoken a few words to the group, People reported.

In lieu of flowers, the Diaz family has suggested donations to Surfrider.org or Reefcheck.org in Emilio's name.

Click here for the People report and to see photos