There was a case a couple of years ago when a driver was fined (and even lost his license I think) after he had been driving too fast with an ambulance behind him on an 2+1 road (
http://en.wikipedia.org/wiki/2%2B1_road)
There were outcrys that this meant that you we're not allowed to speed to let an ambulance pass when driving on a 2+1-road.
The police then showed a reconstruction with the whole stretch of road and there were plenty of places where he could have turned over (a parking/emergency pocket, a turn left lane for example) and thats why it was against the rules.
They say that you should not run a red light to let an emergency vehicle pass here in sweden too.
Sometimes its the best solution however.
I remembered when I was driving over the Lidingö bridge with a bus. They were repairing it so there were only one lane. An ambulance came, with blues and twos, but I couldn't go faster because of the narrow lane. The ambulance actually shut off the sirens until I could move over, instead of stressing behind me.
It seems like there are no serious injuries in the accident between the bus and the tram, and thats good.