Oklahoma authorities are searching for a man they say killed four Chinese nationals and injured another in a shooting at a marijuana farm in Kingfisher County, northwest of Oklahoma City.

The man entered a building at the farm just after sunset, around 5:45 p.m., on Sunday and was inside for a significant amount of time before “the executions began,” the Oklahoma State Bureau of Investigation said in a statement Tuesday.

Brooke Arbeitman, a bureau spokeswoman, said via text message: “These people were executed. Not randomly shot and killed.” She added that the suspect — whose identity authorities are not releasing, because they believe that may put additional individuals in danger — is “considered armed and dangerous.”

Deputies with the Kingfisher County Sheriff’s Office responded to a call Sunday about a hostage situation along North 2760 Road, west of Hennessey, when they arrived at the marijuana farm.

There were “several employees” present with the victims, three men and one woman, authorities said.