Starships have been grounded. The Daedelus and Prometheus are neither available nor assets. The only method of travel is travel through the stargates, which requires knowing gate addresses. Atlantis is still alive and well in the Pegasus Galaxy, but at the start of the game, there is no way for those at the Gamma site to reach her.
The Asgard mobilized to save themselves early on, offering what advice and data and scientific support that they could. Having relied on space travel for so long, they had to retreat to their world and begin the long process of moving millions of collected consciousnesses as well as themselves to another world via the stargate.
The Tok'ra were already difficult to contact and departed with their typical, "We'll let you know when we know something."
There was no sign of danger to Dakara, however, the free Jaffa were still debating whether to remain on Dakara or abandon it when they learned of what happened.
Following the meteor strike, the Gamma Site was not completely devastated. The stargate and the DHD were buried, the secured computer databases were lost and 70% efficiency of the science station was lost. Everyone, even those with no experience in any sorts of disasters, realizes that it could be worse. A good bulk of the surplus supplies were saved, approximately somewhere between 60 and 70 percent. Some temporary housing was destroyed, but families doubled up, and people crammed more makeshift beds and pallets into pre-existing barracks. It's crowded, but not uncomfortable.