According to police, East was found stabbed in the chest at a 76 gas station located at 6322 Westminster Boulevard on Thursday.
East was rushed to the UCI Medical Center where he later died. Eyewitness News learned the coroner listed East as a transient.
Police then named 27-year-old Trent William Millsap as the primary suspect.
On Friday, investigators served a warrant at an apartment in the 3300 block of Lincoln Avenue in Anaheim where Millsap was believed to be located.
"Due to the level of violence he had been exhibiting, the West County SWAT Team was requested to serve the warrant," read a statement issued by the Westminster Police Department.
Police said Millsap became confrontational with officers and an officer-involved shooting occurred.
He was sent to the hospital where he later died.
According to police, at the time of the shooting, Millsap was on parole for armed robbery and had an outstanding warrant for his arrest for an unrelated parole violation.
A motive for the stabbing remains unknown, according to police, and the investigation is ongoing.
East, whose father was a noted short-track car builder, won SAC Silver Crown championships in 2004, 2012 and 2013.
He was just 16 in 2001 when he became the youngest driver to win a feature USAC National Midget race. He won 15 USAC races in 2004 and soon dabbled in a short NASCAR career. He made 11 career starts in what is now NASCAR's Xfinity Series and had two top-10 finishes in 31 career Truck Series races.
"Very sad to hear of the tragic incident involving Legend USAC driver Bobby East. He was one heck of a wheelman," tweeted former Truck Series champion Todd Bodine.
Meanwhile, NASCAR issued the following statement:
"NASCAR is saddened to learn of the tragic death of Bobby East. We extend our deepest and heartfelt condolences to the family and friends of Bobby, a true racer."
The Associated Press contributed to this report.