Clashes spread from the Sadr City district to another Shiite militia stronghold in Baghdad on Sunday as fighting left at least six people dead, including two children, officials said. The US military had no immediate comment on Sunday's fighting but said its forces in Sadr City killed seven armed "criminals" the day before in Sadr City _ two in gun battles and five in two separate airs trikes. The military said it does not engage if civilians are seen in the area. Clashes also broke out between Iraqi forces and militiamen in the southeastern Shiite district of New Baghdad, wounding three people, including a woman, police said. "So I am giving my final warning ... to the Iraqi government ... to take the path of peace and abandon violence against its people," al-Sadr said. "If the government does not refrain ... we will declare an open war until liberation." A full-blown uprising by al-Sadr, who led two rebellions against US-led forces in 2004, could lead to a dramatic increase in violence in Iraq at a time when the Sunni extremist group al-Qaida in Iraq appears poised for new attacks after suffering severe blows last year.