Three children were among the 12 shot dead during a two-hour battle between Iraqi resistance fighters and British occupation forces on Wednesday afternoon.
Doctor Mustafa Ali, speaking at Amara's main hospital, confirmed the casualty figures and said three mortar rounds that landed on the al-Jadida residential district caused the fatalities.
A British military spokesman confirmed bases in Amara, 365km southeast of Baghdad, had come under sporadic small arms fire, but had no information about any "sustained activity".
But resistance fighters loyal to Shia leader Muqtada al-Sadr also fired rocket-propelled grenades and mortars at the governor's house, locals said.
And residents told Aljazeera that a US-led forces aircraft had attacked the commercial district in the town, though there is no information on casualties.
Elsewhere, Aljazeera has learned that six Iraqi national guards have been killed in a missile attack on a check-point in the Alus district, east of the Iraqi town of Haditha.