The four people who were executed Sunday on an Oklahoma marijuana farm were Chinese citizens, state authorities confirmed Tuesday afternoon. 

Three men and a woman – all Chinese nationals – were executed at about 5:45 p.m. on Sunday after a male suspect entered a building on a marijuana grow operation in Kingfisher County, Oklahoma, authorities said. 

An additional victim, also from China, was wounded and air flighted to a metro hospital, according to the Oklahoma State Bureau of Investigation (OSBI). 

Because of a "significant language barrier," next of kin notification is pending, OSBI said in a press release. 

Authorities said earlier Tuesday they have "a suspect in mind" and the killing does appear to be a random incident. They have not revealed how the suspects were killed. 

Law enforcement says they are not releasing the suspect's identity because it will put additional individuals in danger. The case is being investigated as a quadruple homicide.

The farm is about 10 acres, located west of Hennessey, about 55 miles northwest of Oklahoma City.

MARIJUANA LEGALIZED IN THESE STATES IN THE MIDTERM ELECTIONS

The Kingfisher County Sheriff's Office initially responded to a reported hostage situation at the farm but requested help from state authorities, Oklahoma State Bureau of Investigation Capt. Stan Florence said.

Police searched the property late Sunday and Monday using drones, helicopters and on the ground but did not find the suspect, Florence told reporters. 

"There's a lot to unravel with this case," he said. "It'll take a little time for us to process it."

Oklahoma voters legalized medical marijuana in 2018 and the industry boomed due to an open-ended law that put in place fewer restrictions than in other states.

In March, voters will decide whether to legalize the recreational use of the drug.

The Associated Press contributed to this report.