What to do about unsafe stray dog in building?

I live on the 2nd floor, which is the top floor. The residents of the 1st floor have placed a mattress and food in the common stair area on the ground floor. The space is very small and also contains electric meters. The mattress takes up about one-fourth of the area. They feed stray dogs but refuse to adopt or leash them, making the area unsafe. Delivery people and guests often feel threatened by the dog, and we don’t know if it’s vaccinated. We’re not against the dog, but we want them to keep it inside their apartment. Why should other residents suffer? Is there anything we can do for a peaceful solution?