Unknown gunmen have shot and killed a female radio journalist in Somalia in the latest of a string of fatal attacks targeting members of media in the lawless Horn of Africa nation.

On Monday, colleagues and witnesses said two men armed with pistols killed 25-year-old Rahmo Abdulqadir Farah, who worked for the private Radio Abduwaq station, late on Sunday, The Associated Press reported.

"One of our female staff members was shot and killed in Mogadishu," Abdikarim Ahmed Bulhan, the director of the radio station, said.

"We don't know why she was killed but we are in shock," he added.

Witnesses said men approached the reporter before firing repeatedly and then ran away.

"Two men armed with pistols shot the woman... they fired their guns five times before fleeing," Abdi Moalin Shire, a witness, said.

"There was another girl who accompanied the victim but the gunmen did not target her, she ran away screaming for help," Issa Mohamed, another witness, said.

No group immediately claimed responsibility for the killing. The incident brings the number of journalists killed in Somalia so far this year to three.

Somalia is one of the world's most dangerous places for journalist to work. At least 18 media workers were killed in 2012 in the country, mostly in targeted killings. No one has been charged with the murders.