They don't need to. Fleeing the scene after shots were fired from that car, wounding a person? [While perhaps only confirmed after the fact, the guns in the car show that it was the right car.] That's a solid case of a fleeing felon who can reasonably be presumed to pose a risk to others.
Tennessee v. Garner, 471 U.S. 1.
A police officer may not seize an unarmed, nondangerous suspect by shooting him dead...however...Where the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force.
— Justice Byron White
Are you sure that this car was the suspect car?
If so, why?