(CNN) — Seven aid workers who were kidnapped in Yemen have been released, the United Nations said in a statement Thursday.

The workers, who were abducted Tuesday, are unharmed, said Valerie Amos, U.N. under-secretary-general for humanitarian affairs and emergency relief coordinator. They were in the Yemeni capital of Sanaa on Thursday and are in contact with their families, she said.

A senior Yemeni Interior Ministry official said Tuesday that tribesmen intercepted the workers’ vehicles in Mahweet province and took them to an unknown destination. The official initially reported that six workers had been kidnapped: two Yemenis, a German, an Iraqi, a Palestinian and a Colombian.

“I would like to sincerely thank the Yemeni authorities and all those who worked tirelessly to secure the safe release of our colleagues,” Amos said in the statement Thursday.

“This incident serves to remind us of the dangers faced every day by humanitarian workers helping people in crisis situations around the world. Their only aim is to provide assistance and protection to people in need,” Amos said.

Mahweet is about 65 miles north of the Yemeni capital of Sanaa. Residents in the area said the kidnappers were seeking the release of a man being held at the central security prison on suspicion of minor crimes.

Kidnappings are common in Yemen. A Norwegian working for the United Nations, who was kidnapped by tribesmen from Mareb province, was released this week.

— Journalist Hakim Almasmari contributed to this report.