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Flowers are seen at a memorial outside of the offices for WDBJ7 where slain journalists Alison Parker and Adam Ward worked in Roanoke, Virginia August 27, 2015. Parker, 24, and Ward, 27, were shot dead on Wednesday during a live segment for the CBS affiliate in Roanoke, Virginia, at a local recreation site about 200 miles (320 km) southwest of Washington. Another woman was wounded. The suspected gunman, 41-year-old Vester Flanagan, later died from a self-inflicted gunshot wound, authorities said. REUTERS/Chris Keane

Robert Seth Denton has been arrested for the murder of his mother, stepfather and grandmother in front his six siblings on Saturday. The 19-year-old carried out the killings at his family’s mobile home in Tennessee, USA. He walked in with 100 rounds of ammunitions in a camouflage clothing.

"From what I've seen and heard, he just took them by surprise," eastern Tennessee Sheriff Wayne Anderson told the Associated Press. "It just all happened real fast."

Apart from the gruesomeness of the murder, what struck the attention of the police most is the fact that Denton went up to his grandfather Curtis Rose, and instead of shooting him dead like the others, he asked him to call the 911. "Why he didn't shoot his grandfather and went out there and told him is beyond me," Anderson added to the AP.

At the time of the crime, Denton was not living with his family in their mobile home. He lived in an apartment in Briston. At first, his relationship with the family was not clear since he did not live with them. On Saturday evening, he walked in with a gun and fired at his parents and grandmother. His grandfather could not hear the gunshot over the noise of his power tools, as he was working on the neighbouring trailer when the murders took place.

The local T.V. Station reported that after Denton told him about the murders, Rose took the children to another room, grabbed a gun for safety and informed the police. When he came out he found his grandson walking back down the driveway. He followed in a van and shot Denton in his arm.

One of the siblings got injured and the teenager has been charged with three counts of first-degree murder, felony reckless endangerment and aggravated assault. However, the grandfather had been acquitted of all charges for shooting at his grandson.

"We have gained a lot of information that he has hated his mother for most of his life," Anderson said. "He had made statements over the years that he wanted to kill her."

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