The Somali security forces are hunting for the gang which kidnapped two women who work for an aid agency.
The pair, a Spanish doctor and an Argentine nurse, were seized near the northern port of Bossasso, in the semi-autonomous region of Puntland.
They work for the aid agency Medecins Sans Frontieres (MSF).
A French journalist was freed on Monday more than a week after being captured in the same region. Police denied that any ransom had been paid.
A Puntland official told the AP news agency that the kidnappers were "holed up in a mountainous area".
Another official, Ahmed Aaid Aw-Nour, said one of the kidnappers was arrested during the kidnap.
"Now there is a military operation as we have sent more troops to where the aid workers are staying," he told Reuters news agency.
Puntland government officials and elders said last week that the abductors had asked for a ransom of $70,000 (£35,000) to release journalist Gwen Le Gouil.
He was in Bossasso to shoot a documentary on the mass smuggling of refugees from Somalia and other war-torn Horn of Africa countries across the Gulf of Aden to Yemen when he was captured on 16 December.
Puntland has generally been more stable than southern Somalia since the country last had an effective national government in 1991.