TEHRAN, Iran (CNN) -- An explosion rocked a mosque in southeastern Iran on Thursday, killing at least 15 people and wounding more than 50, Iranian news outlets reported.
The explosion took place in Zahedan during evening prayers on a Muslim religious holiday, Ali-Mohammad Azad, the governor of Iran's Sistan and Balochistan province, told the Iranian television network IRIN.
Worshippers were marking the 7th-century death of Fatima, the daughter of the prophet Mohammed, when the blast went off about 7:45 p.m. (11:45 a.m. ET), Azad said.
Azad said at least 15 people were killed at the Amir Al Momenin mosque. The semi-official news agency Fars put the death toll at 20, with at least 55 more wounded.
Zahedan is about 1,100 km (700 miles) southeast of Tehran, near Iran's borders with Pakistan and Afghanistan.
Fars attributed the explosion to a "terrorist incident," but said no claim of responsibility had been received.
In April 2008, a blast at a mosque in the southern city of Shiraz killed 13 people and wounded more than 200.
Iran's government originally blamed the blast on a homemade bomb, but then said it was caused by negligent handling of live ammunition from an exhibit on the Iran-Iraq war of the 1980s.
A government minister later said the blast was the result of sabotage and said the suspects had links with Western countries.
Shirzad Bozorgmehr contributed to this report for CNN.