A bomb in a mosque in south-east Iran has killed at least 15 people and wounded 50, the governor of Sistan-Baluchestan province said. The explosion happened in Zahedan, the provincial capital, at the time of evening prayer, Ali Mohammad Azad told Iranian state TV. The province is often the scene of lawlessness, including clashes between police and drug dealers or militants. Zahedan is a mainly Sunni Muslim city in a mostly Shia state.