Had it been dry for a long time without raining? When it rains for the first time after a long period the road can get very slippery, this usually only happens in the summer though.
There could be two reasons for the loss of traction : You were demanding too much from the tyres The tyres didn't have enough grip
I suspect that it was a bit of both, wet roads make a huge difference! The grip is 'shared' between the steering and acceleration. So if you are steering hard you won't be able to accelerate so hard.