Source. According to the source, the guy has worked a few days prior. On October 20th, he shot his boss over a paycheck typo. He tried to cash it but his middle initial was incorrect. The company wanted him to bring the check back so they could fix it, but he had already ripped it in frustration. When he went to the company, the boss told an assistant to make a new check. Before that could happen, he pulled out the gun and shot. Police questioned the man, he said he wasn't allowed to be armed due to previous felony convictions.
Go here and you can get a bit more info and see the mugshot.