Kurdish fighters have made rapid gains
US-backed Kurdish forces have occupied the centre of the northern Iraqi city of Kirkuk.
Government buildings were set ablaze and a statue of Saddam Hussein was pulled down by jubilant crowds, mirroring scenes in the capital, Baghdad, a day before.
Neighbouring Turkey - hostile to any Kurdish independence moves - has voiced concern, and announced it is sending military observers to Kirkuk.
The BBC's Dumeetha Luthra in Kirkuk says that after the elation of the day, the streets have fallen quiet as people are unsure what the night will bring.
Earlier, Kurds had gone on a looting spree.
Kurdish commanders told the BBC's John Simpson that their fighters had entered Kirkuk in disguise overnight and started an uprising.
According to one senior US official, the Kurds jumped the gun with their move into the city.
The capture of Iraq's fourth-largest city could have major ramifications as different groups position themselves for power in post-war Iraq.
Turkish Foreign Minister Abdullah Gul said "everything is being followed very closely".
The Turkish military observers are being sent - with US approval - to ensure the Kurdish fighters withdraw from the city.
Kurdish commanders have told our correspondent that the troops will withdraw to barracks outside the city which have been evacuated by the Iraqi forces.
US Secretary of State Colin Powell had given assurances, Mr Gul said, that extra US troops would arrive there soon.
The BBC's Jonny Dymond in Istanbul says that Turkey fears the oilfields surrounding Kirkuk could give an economic foundation to Kurdish hopes for an independent state.