The violence in the region is escalating...
Russian jets have carried out strikes on military targets in the central Georgian town of Gori, close to the breakaway region of South Ossetia.
Most of the targets seem to have been military bases, but Georgian officials said a number of civilians had been killed in residential buildings.
Russia said it had "liberated" the South Ossetian capital, Tskhinvali.
Earlier, Russian President Dmitry Medvedev said his country was seeking "to force the Georgian side to peace".
The comments came after Russian commanders announced they were sending more troops into South Ossetia to support peacekeeping operations.
The Russian defence ministry confirmed two of its jets had been shot down over Georgia, although it did not say where.
In a live televised address, Georgian President Mikhail Saakashvili said he would ask parliament to approve the introduction of martial law.
After days of exchanging heavy fire with the Russian-backed separatists, Georgian forces launched a surprise attack on Thursday night to regain control of the region, which has had de facto independence since a war in 1992.
Georgian troops in the city of Gori (NY Times)
A small contingent of US troops is in Georgia, and since Russian forces are attacking Georgian military installations, it is not known if they are in imminent danger:
About 130 U.S. military and civilian personnel are currently located in Georgia, where they are training Georgian troops for deployment to Iraq as part of the multinational force there. U.S. military officials in Baghdad said they had gotten no official word about statements from Tblisi that half of Georgia's 2,000-troop contingent was being called home.
It isn't something that is front and center in the reporting, since attacks on civilians are the real story here. But when you start to think about why the sides are fighting, it really does come down to energy revenues:
The BBC's Richard Galpin in Gori heard loud explosions and saw large plumes of smoke rising into the sky; soldiers and civilians were seen running through the streets.
One missile hit a military base, from which most of the soldiers appeared to have managed to escape beforehand, he says.
The Georgian military said residential buildings had also been struck, leaving a number of civilians dead. Our correspondent says injured civilians were being pulled from the buildings, which were on fire.
The Georgian foreign ministry said the Black Sea port of Poti, which is the site of a major oil shipment facility, had also been "devastated" by a Russian aerial bombardment.
Georgian troops riding to the front (NY Times)
The US and the United Nations seem ineffectual, unable to get past the Russian veto on the Security Council:
International Red Cross (ICRC) spokeswoman Anna Nelson said the ICRC had received reports that hospitals in the city were "overflowing" with casualties.
The BBC's James Rodgers in Moscow says diplomatic initiatives to end the fighting have so far proved fruitless.
On Friday evening, the UN Security Council failed to agree on the wording of a statement calling for a ceasefire.
Russia holds a permanent place on the Council, and has the power of veto over any official statements that it regards as unfair or inaccurate.
Permanent members Britain, the US and France, are pinpointing what they say is Russia's aggression as the key factor in the slide towards war, while Moscow insists Georgia is to blame.
In other developments:
US Secretary of State Condoleezza Rice called on Russia to pull its troops out of Georgia and respect its territorial integrity
Georgia's president said his country was withdrawing its contingent of 2,000 troops from Iraq to help deal with the crisis
The European security organisation, the OSCE, warned that the fighting in South Ossetia could escalate into a full-scale war
The US and the EU were reported to be sending a joint delegation to the region to seek a ceasefire and Nato said it was seriously concerned.
She needs to go to Moscow and/or the region immediately. Not some envoy, not some flunky--she's the expert on Russia, and her area of expertise has so far proven to be an area of foreign policy in which she's about as effective as everywhere else she tries her hand--and that's not very damned much.