Three persons, including the gunman, have been killed in a shooting incident in Houston in the US state of Texas, police said.Houston Police Department Executive Assistant Chief Troy Finner told reporters on Friday in a briefing that the shooter, who was a former employee of an auto repair shop, shot and killed two employees at the shop, Xinhua news agency reported. The shooter then walked out to the yard and shot himself dead, said the police officer.Finner said there were multiple people inside the shop when the shooting happened. He said police have contacted the family of the shooter, but declined to confirm the gender of the shooter.No other injuries have been reported. The motive for the shooting is unknown at this time. Police said more detailed information would be released after investigation.