Aid workers and journalists who know the three Japanese kidnapped by a militant group in Iraq expressed grave concern over the situation Friday, with some vowing to do whatever it takes to bring them back alive.

"We are very shocked by the news," said Michio Kumaoka, head of Japan International Volunteer Center, a Tokyo-based group that is providing medical aid to three hospitals in Baghdad and Basra. "It could have been us."

His staff have exchanged information in Baghdad on a number of occasions with Nahoko Takato, one of the three Japanese captives. They frequently helped Takato because she was mostly working on her own with a very limited budget.