Gunmen in central Somalia have kidnapped three aid workers – an American woman, a Danish man and their Somali colleague.

The three work for the Danish Demining Group, which says they were kidnapped Tuesday afternoon in the city of Galkayo, while on their way to the airport.

It is not clear who carried out the abductions.

An employee with the demining group told VOA that the hostages were taken unharmed.

The employee, who requested anonymity, said the abductors are heading toward the port town of Hobyo with two of the hostages. Hobyo is considered a major pirate hub.

Over the past month, gunmen have kidnapped four foreigners in northern Kenya and taken them into Somalia. The kidnap victims included two Spanish nationals working for the medical aid agency Doctors Without Borders.

The Kenyan government blames those kidnappings on the Somali militant group al-Shabab, and has sent troops into Somalia in pursuit of the militants. Al-Shabab denies it had anything to do with the kidnappings.

The United States condemned the kidnapping Tuesday. A spokeswoman for the State Department, Victoria Nuland, said officials are working to establish the identity of the kidnapped U.S. citizen.

The Danish Demining Group is involved in clearing mines and unexploded ordnance in conflict zones in Africa and the Middle East. The group has suspended its activities in the area where the three workers were kidnapped while the investigation is ongoing.