WASHINGTON (AP) — An Air Force investigation into alleged drug use in the ranks has expanded to include 10 officers at six bases in the U.S. and Britain.

Nine lieutenants and one captain are being investigated for illegal possession of recreational drugs, Air Force spokesman Lt. Col. Brett Ashworth said Friday. The case began with the investigation of two officers at Edwards Air Force Base in California and quickly widened to several other bases because of the airmen’s contacts with others about drug possession, he said.