Police are searching for the suspect, identified as Dakota Theriot [Source: LIVINGSTON PARISH SHERIFF]

Police in the US state of Louisiana are searching for a gunman suspected of killing five people in two separate but related shootings.

The shootings happened in the parishes of Ascension and Livingston, south of the state capital of Baton Rouge.

Authorities say 21-year-old Dakota Theriot fled in a gray and silver Dodge Ram pick-up truck. The victims include his parents.

Ascension Parish Sheriff Bobby Webre said he was “armed and dangerous”.

On Saturday morning local time, police were called to a trailer park in the city of Gonzales, 25 miles (40km) south of Baton Rouge, for a “domestic incident”, Sheriff Webre said.

When they arrived, they found two people who had been shot but were still alive. They have been identified as Elizabeth and Keith Theriot, both 51 years old.

They told the officers that their son – who had recently been told to leave their house and not return – was the shooter.

The couple were taken to a hospital in Baton Rouge where they later died.

“This is probably one of the worst domestic violence incidents I’ve seen in quite a while,” Sheriff Webre said.

Reports suggest the gunman first killed three other people in neighbouring Livingston Parish.

The victims were not relatives of the suspect but knew him, Sheriff Webre said. They have been identified as Billy Ernest, 43; Summer Ernest, 20; and Tanner Ernest, 17.

It is suspected that he stole the vehicle from them and was headed to the neighbouring state of Mississippi.

The suspect is wanted for first-degree murder, illegal use of weapons and home invasion.