As details of Paul Walker's sudden death continue to unfold, the 40-year-old actor's Fast and Furious costars mourned his passing on social media.
Walker died Saturday in a car crash in Santa Clarita, Calif. Leaving a charity event, he was riding in the passenger seat of a Porsche Carrera GT, when the driver lost control. The car slammed into a post or a tree, and burst into flames, according to a report.
See also: Fast and Furious Actor Paul Walker Dead at 40
Walker was best known for his role as Brian O'Conner, a police officer in five of the soon-to-be seven films in the Fast and Furious franchise. He co-starred alongside Vin Diesel, who expressed his grief on Instagram, saying he was "absolutely speechless."

In one of his last interviews before the crash, Walker told USA Today on Monday that fans addressed him more often by his signature character's name than by his real name — so much so, in fact, that he felt more comfortable when identified as his Fast and Furious alter ego.
"I'm Brian a lot more than I'm Paul Walker, which is awesome," Walker told the newspaper. "When I hear, 'Hey Paul Walker!' my hair stands up on the back of my neck. It's uncomfortable. But when I hear 'It's Brian!' it's cool. I like Brian."
The tight-knit cast expressed their condolences to Walker's family via social media.
All my strength, love & faith to the Walker family during this heartbreaking time. We find our strength.. in his light. Love you brother.
— Dwayne Johnson (@TheRock) December 1, 2013
Paul was pure light. I cannot believe he is gone.
— Jordana Brewster (@JordanaBrewster) December 1, 2013
I am so beyond heartbroken right now. I can't process anything.
— James Wan (@creepypuppet) December 1, 2013
Dear Paul... Sleep with the Angels... pic.twitter.com/1hJDMyTxHt
— Adam Shankman (@adammshankman) December 1, 2013
Perhaps the most heartbreaking of all is a screenshot of a text exchange between Walker and co-star Tyrese Gibson, who plays Roman Pearce, a childhood friend of O'Connor's in the films.
Gibson shared their last conversation on Instagram, adding, "At least I got to say I love you."

Rapper Ludacris, a long-standing Fast and Furious cast member who plays Tej Parker, another friend of O'Connor's, shared a photo of the cast on Instagram.

"Your humble spirit was felt from the start, wherever you blessed your presence you always left a mark, we were like brothers & our birthdays are only 1 day apart, now You will forever hold a place in all of our hearts @paulwalker legacy will live on forever. R.I.P.," the photo's caption said.
Image: Stuart C. Wilson/Getty Images for Universal Pictures