Two Canadian aid workers who were among a group of four people abducted at gunpoint from Kenya's largest refugee camp returned safely to Nairobi on Monday, flown back by a military helicopter after a daring rescue operation inside Somalia.

The Norwegian Refugee Council, which employs the four aid workers, identified them as:

• Steven Dennis of Toronto, 37.
• Qurat-Ul-Ain Sadazai, 38, of Gatineau, Que.
• Glenn Costes of the Philippines, 40.

• Astrid Sehl of Norway, 33.

The workers smiled and waved after landing in Nairobi.

"We are happy. We are back. We are alive and we are happy this has ended," Sadazai said.

Released foreign aid workers arrive in Kenya's capital Nairobi on Monday. (Thomas Mukoya/Reuters)

Elisabeth Rasmusson, the aid group's secretary general, told a news conference in Oslo, the Norwegian capital, that she was relieved the four had been released.

"What we know right now is that they have been released and are in good condition," she said.

Canadian officials also expressed relief at the news Monday.

"We are elated by the safe rescue of Canadian citizens taken hostage in Kenya," a spokesman for the Department of Foreign Affairs said in an email.

Jean-Bruno Villeneuve said the High Commission in Nairobi would provide support for the Canadian workers.

Canadians were veteran aid workers

The rescued Canadians were described on Monday as seasoned aid workers dedicated to humanitarian causes.

Rolf Vestvick, director of advocacy and information for the Norwegian Refugee Council, said both Sadazai and Dennis knew the dangers associated with helping the poor in potentially volatile regions of the world.

"The places where the refugees are in need of humanitarian aid is very often high risk areas," Vestvick said. "So it is something that everybody working in this business is aware of."

Sadazai had just returned to Kenya in February to take on the role of deputy director of the NRC's operations in Somalia and Kenya. She had worked there from 2007 until 2010, leaving for a couple of years to head up the agency's operations in Peshawar, Pakistan.

Dennis had only worked for the Norwegian Refugee Council for the past year in Kenya, but had a lengthy background in humanitarian work with other agencies, including Doctors Without Borders.

Abdinasir Serar, a representative with the pro-government Ras Kamboni militia in Somalia, said his group heard of Friday's abduction in Kenya's Dadaab refugee camp and pursued the abductors. Ras Kamboni fighters caught up with the abductors Monday morning about 60 kilometres inside Somalia.

1 abductor killed

Ras Kamboni's leader, Ahmed Madobe, said his men killed one of the abductors but that the other three escaped. The rescue happened in the village of Alu Gulay.

The four rescued workers were taken to the Somali town of Dhobley and were then flown to Nairobi. Ras Kamboni works alongside Somali government and Kenyan military forces. Kenya sent troops to Somalia last October to hunt al-Shabaab militants.

The aid workers were abducted in Kenya's Dadaab refugee camp, 100 kilometres from the Somali border. (Google)

The workers were taken on Friday, when four gunmen attacked a two-vehicle convoy from the Norwegian Refugee Council, killing one Kenyan driver and wounding two other Kenyans. The gunmen took one of the two vehicles and the four workers. The group later abandoned the vehicle and began walking toward the Somali border.

Rasmusson was present during Friday's attack but was not harmed or taken. She said Friday that the attack happened on a main road toward the city of Dadaab in "what is recognized as the safe part of the camp."

One of the four held captive was wounded in the leg.

A Kenyan police commander said the aid group originally arranged to have armed security travel with it but that the group cancelled the security arrangements at the last minute.

After an attack on a Doctors Without Borders convoy last year in which two Spanish women were abducted, some aid groups began using security escorts in Dadaab, a series of sprawling camps connected by sandy roads.

With files from CBC, The Canadian Press