More arrests are expected following the killing of Roger Gower, who was on a joint operation with Tanzanian wildlife authorities when he was shot, the Friedkin Conservation Fund said Friday.
Those detained include the suspected gunman and accomplices, as well as "members of a criminal network providing illegal firearms and facilitating the transport and sale of ivory," the Texas-based Friedkin group said in a statement.
Two days after Gower's death, the group announced three arrests in an ongoing security operation.
Tanzania has been identified as a key hotspot for elephant poachers. The elephant population declined by 60 percent to about 40,000 since 2009, according to a census announced last year.