Check out this article at MSNBC. In short, two officers show up at the scene of an accident. Find two gunshot victims yards apart on the side of the highway. Police try to help gun shot victims, and are fired on themselves. Officer gets wounded. Passers by show up, and are also are fired on. One passer by retrieves a pistol from his car, shoots gunman dead.
You gotta love Texas. Hat tip to Syd of Front Sight, Press
UPDATE: The article updated to say the suspect shot himself.