A 21-year-old Louisiana man wanted in connection with the shooting deaths of his parents and three other people was arrested at gunpoint Sunday at his grandmother's home in Virginia, authorities said.

Dakota Theriot will be transported from Virginia's Richmond County to Ascension Parish in Louisiana and booked on two counts of first-degree murder, home invasion and illegal use of weapons, Parish Sheriff Bobby Webre said.

Theriot’s grandmother had spent the night in a hotel because she feared her grandson might come to her home in Warsaw, Richmond County Sheriff Stephan Smith said. The woman asked authorities to check her home Sunday morning to make sure it was safe before she went home.

"While deputies were on site, Theriot arrived at the residence in a motor vehicle with a firearm pointed out of the window," Smith said in a statement. "The deputies sought cover and challenged Theriot, who then dropped the firearm upon their commands and was taken into custody without incident."

Theriot was held without bond at Northern Neck Regional Jail pending a court hearing, Smith said.

Authorities suspect Theriot fatally shot Billy Ernest, 43, his son Tanner, 17, and daughter Summer, 20, in their Livingston Parish home early Saturday before driving to his parents home. A short time later, Ascension Parish deputies were called to the couple's trailer in the city of Gonzales, where they found Dakota's parents, Elizabeth and Keith, both 51, with gunshot wounds.

"The father was gravely injured at the time we found him and has since passed away," Webre said. "We were able to get a dying declaration from him, only enough information to let us know it was his son that committed this act."

Elizabeth Theriot died from her wounds a short time later.

Webre said Dakota Theriot lived with his parents briefly but was asked to leave and not return. Kim Mincks, who lived with the couple, said the son had a loving relationship with his mother but engaged in sometimes violent arguments with his father.

Livingston Parish Sheriff Jason Ard said Theriot had recently been in a relationship with Summer Ernest. He said he had spoken with Summer's mother, and "there were no red flags, no sign of anything. We have no motive at this time."

Crystal DeYoung, Billy Ernest’s sister, told The Associated Press that she believes Theriot and Summer had just begun dating.

“My family met him last weekend at a birthday party and didn’t get good vibes from him,” DeYoung said. “My mom is a good judge of character, and she just thought he was not good."

The Ernests' neighbor, Charlene Bordelon, told The Advocate the two youngest children in the Ernest family fled to her home after the shooting. Bordelon said the two children, both under 8 years old, were not wounded. Bordelon called 911 after the children told her their father, brother and sister were dead.

"She was terrified," Bordelon said of the little girl. "It's so heartbreaking."

Webre said Theriot did not have a police record in Ascension Parish, but he did have run-ins with law enforcement in St. John, St. Charles and Jefferson Parishes.

"He was not on our radar screen in Ascension Parish," Webre said.

Contributing: The Associated Press