Who is the first to respond in a chain of effects?

[Shapeshifter]

Given the case a company wants to travel through at least one and Snowstorm is already in play at the beginning of the m/h-phase. First thing that will happen is the triggering of this passive condition to which both players could respond by playing a card in this chain of effects, right?

Now for my question: who is the first player that has to respond?

This could be important in the following example:
Player 1 (resource player) likes to play Twilight to cancel Snowstorm’s effect but wants to wait with it until he knows if player 2 responds.
Player 2 (hazard player) would play a hazard card before Snowstorm’s effect causes the company to return to its site of origin and its m/h-phase immediately ends. But only if player 1 doesn’t respond with Twilight. Otherwise he would rather play a different hazard card.

Probably the answer is too obvious for me to see it.

[Bandobras Took]

I'm not sure of a rule to back me up, but I would maintain that the hazard player would have been considered to declare actions declared by the passive condition of a hazard.

[Sauron]

The resource player has 1st priority, if he passes then the hazard player gets priority. If he passes then condition goes off.

Each player gets to respond to the other players play, until both pass.