The incident happened just after 11 a.m. near Pickering Avenue and Penn Street, close to St. Mary of the Assumption Elementary School.
When officers got to the scene, they found the man slumped over the driver's seat of a beige Saturn.
"I was in the house, I heard a gunshot and came outside and didn't see anybody," said a neighbor named Christopher who spoke with Eyewitness News. "A few minutes later, cops pulled up."
No other injuries were reported and the suspect remains at large as of Thursday afternoon.
"God forbid there was no children around or other people around," said Christopher. "I have two twin toddlers, and it's scary to know that this happened in broad daylight."
Anyone with information is urged to contact Whittier Police Department Dispatch at 562-567-9240.