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A manhunt is underway for a Louisiana man suspected of a Saturday morning killing spree that has left five people dead, including his parents.

Authorities said that Dakota Theriot, 21, is suspected of fatally shooting a woman believed to be his girlfriend and her father and her brother at their home in Livingston Parish, where the suspect had been living for a couple of weeks, before traveling to Ascension Parish where he killed his mother and father.

"We do not have a motive. It is still undetermined," Livingston Parish Sheriff Jason Ard said. He said investigators spoke with the mother of the slain woman believed to be Theriot's girlfriend, Summer Ernest, 20, and were told that "there was no red flags, there was no sign of anything."

In Ascension Parish, Theriot's wounded father gave deputies information before he died that pointed to his son as the suspected shooter, Ascension Parish Sheriff Bobby Webre said.

Webre said at a news conference Saturday afternoon that deputies responded to the Theriot home in Gonzales, about 25 miles southeast of Baton Rouge, at around 8:45 a.m. CST, and found the suspect's parents, Keith and Elizabeth Theriot, shot.

Dakota Theriot is wanted for two counts first-degree-murder, illegal use of weapons, and home invasion. Ascension Parish Sheriff's Office

At the time, Keith Theriot was still alive and gave information to officers "that his son, Dakota Theriot, is going to be our prime suspect in this case," Webre said. The parents were airlifted to a hospital in Baton Rouge where they later died.

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"This is probably one of the worst domestic violence incidents I've seen in quite a while: for a young man to walk into a bedroom and kill his mother and his father" and others in Livingston Parish, Webre said Saturday afternoon.

Before the killings in Ascension Parish, Dakota Theriot is believed to have fatally shot Summer Ernest, her father Billy Ernest, 43, and her brother, Tanner Ernest, 17, in Livingston Parish, Ard said.

Theriot left in Billy Ernest's 2004 Dodge gray and silver pickup truck at around 8:05 a.m., Ard said. He traveled to Ascension Parish where he went inside his parents' trailer and shot his mother and father, Webre said.

The Ernests' neighbor, Charlene Bordelon, told The Advocate newspaper of Baton Rouge that the family’s two youngest children, both under 8 years old, ran to her home Saturday morning after the shooting asking for help. Those children were not injured, she told the newspaper.

Webre said that the suspect had lived with his parents for a time, but recently they had asked him to move out and not return. The sheriff did not know any background information about the young man's relationship with his parents.

The Bordelons, the neighbors of the Ernest family, told The Advocate that Theriot was the boyfriend of the Ernests' older daughter and had recently moved in with them. They told the newspaper that they did not know Theriot.

The suspected gunman is now wanted on two counts of first-degree murder and one count each of illegal use of weapons and home invasion, for the killings in Ascension Parish. Ard said Theriot is also charged with three counts of first-degree murder for the killings of the Ernest family members, as well as theft of a motor vehicle.

Authorities believe that Theriot headed east and he may be in another state, Webre said. Ard said they believe he is armed with at least one handgun.

"There's no reason for us to believe that there's anybody else who is a target, other than I will say he is an armed and dangerous guy: so anybody he comes in contact with could be a target," Webre said Saturday afternoon.

Theriot doesn't appear to have a criminal history in Ascension Parish but does have some history in St. John, St. Charles and Jefferson Parishes, Webre said, but he said none of those cases involved violence and they were theft and misdemeanor-type situations.

"Certainly nothing of a great magnitude as we see today," Webre said.

The Ascension Parish Sheriff's Office and Livingston Parish Sheriff's Office are working together alongside the Louisiana State Police to locate Theriot.

"The good news is that we know who did this," Webre said, "and we will soon find this person and put him in jail where he belongs."