The sirens were in fact coming to get Peter. The ambulance from Peter's own hospital pulled up in his yard, despite the fact that Peter had been going to a doctor at a different hospital. They had been closer and they knew Peter well, obviously.

Katia was with them, and she raced into the house ahead of the paramedics. "Tasha! I...oh god..." Katia said, as she saw Peter's still form on the floor. "Oh, no...."