Tesla Inc. accused a fired employee of threatening workplace violence at its Gigafactory battery production facility in Reno, Nev. "Yesterday afternoon, we received a phone call from a friend of Mr. Tripp telling us that Mr. Tripp would be coming to the Gigafactory to 'shoot the place up.' Police have been notified and actions are being taken to enhance security at the Gigafactory," a Tesla spokesman said in response to an email seeking comment on the employee, Martin Tripp. Tripp was accused of sabotage by Chief Executive Elon Musk in an email late Sunday night, and Tesla fired him Tuesday and sued him Wednesday. Tripp, though, spoke to The Washington Post and CNNMoney on Wednesday evening and claimed to be a whistleblower seeking to expose dangerous practices and inaccurate public statements at Tesla. Tesla shares were trading nearly 3% lower Thursday, but have increased 13.6% so far this year as the S&P 500 index has gained 3.5%.