LACEY, Okla. (AP) — State police in Oklahoma said Tuesday that four people killed at a marijuana farm were executed, and that they were Chinese citizens.

The Oklahoma State Bureau of Investigation said three men and one woman were killed on the 10-acre (4-hectare) farm west of Hennessey, about 55 miles (90 kilometers) northwest of Oklahoma City. A fifth victim who was wounded was taken to a hospital.

State police said next-of-kin notification is pending “because of a significant language barrier.”

Police have made no arrest but said they have “a suspect in mind.”

“Based on the investigation thus far, this does not appear to be a random incident,” OSBI said in a news release.

Police have not said how the victims were killed.

THIS IS A BREAKING NEWS UPDATE. AP’s earlier story follows below.

LACEY, Okla. (AP) — Authorities have “a suspect in mind” after four people were found dead and one injured at a marijuana farm in rural Oklahoma, but no arrests have been announced.

Oklahoma State Bureau of Investigation Capt. Stan Florence said authorities believe the suspect knew the victims, who were found dead Sunday night at the 10-acre (4-hectare) farm west of Hennessey, about 55 miles (90 kilometers) northwest of Oklahoma City.

“They all know each other,” Florence said. “Don’t know if they’re related, or if they’re coworkers, but certainly these individuals were, we believe, all familiar with each other.”

Authorities have not identified the victims or said how they were killed. The injured person was taken to an Oklahoma City hospital. The case is being investigated as a quadruple homicide.

The Kingfisher County Sheriff’s Office initially responded to a reported hostage situation at the farm but requested help from state authorities, Florence said.

“At this point, we have a suspect in mind,” Florence told reporters Monday at the property. “We have no information specific to be able to share … at this point.”

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

“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 quickly boomed, thanks 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.