Young NASCAR driver Jason Leffler died tonight after a horrible dirt car crash at the Bridgeport Speedway in New Jersey. Fans and colleagues took to Twitter to mourn the 37-year-old racer.

Leffler leaves behind a 5-year-old son, Charlie, who just finished kindergarten. Friends and fans note how Leffler’s poignant Instagram account shared beautiful moments with his son.

Here are some of Leffler’s last tweets:

Deepest condolences to Leffler’s family. R.I.P.