(CNN) -- At least 12 people, mostly women, were killed and 47 others were wounded in Somalia's capital city, Mogadishu, after Islamists and African Union forces exchanged shells Thursday, an ambulance service official said. "I can confirm that at least 12 people died in today's fighting and we have collected 47 others who got wounded," said Ali Musa, director of an ambulance service who spoke to CNN from Mogadishu. "At one site, a shell landed on women selling milk and a number of them got killed and wounded." Exclusive: Somalia battles measure success in meters . Musa said the shelling began in the morning with Islamist rebels firing mortars at Somalia's parliament building, where lawmakers were in session. The exchange of shells continued until 3:20 in the afternoon, Musa said.
Rebels fired mortars at the parliament building in Mogadishu . African Union forces fired shells in return .