London (CNN)A British national who was taken hostage in Nigeria has been killed while three others have returned home safely.
Ian Squire was killed after being kidnapped on October 13. Abducted at the same time were Alanna Carson, David Donovan and Shirley Donovan, according to a statement Monday by the hostages' families and the UK foreign office.
The families said that Nigerian authorities had helped negotiate their release and they thanked British authorities for their "support."
"We are delighted and relieved that Alanna, David and Shirley have returned home safely. Our thoughts are now with the family and friends of Ian as we come to terms with his sad death," they said.
"This has been a traumatic time for our loved ones who were kidnapped and for their families and friends here in the UK."
The statement did not make clear who was behind the abductions. An investigation into the incident is ongoing.
The four were kidnapped in the country's oil-rich southern Delta region, Nigerian police there told CNN.
In its travel advice, the UK foreign office warns there is "a high threat of criminal kidnap" in the Delta area and advises against all but essential travel there.