Since the war in Ukraine started there are volunteers and organizations that help people from Ukraine to get to Bulgaria. One of these options is organized by Bulgarian's Ministry of Defense Ministry of Foreign Affairs.
Currently, there is a daily bus that arrives at Siret everyday around 11:00 Romania time (BST +2) and leaves for Ruse when it gets full, which is around 2:00 PM at the moment. The buses have the Bulgarian flag in the front window and a sign that they are free of charge (безкотошовно).
There are similar buses from Giurgiulești and Isaccea to Varna.
If people arrive later, they can stay in a hotel for free and take the bus the next day. If one has any further questions please contact the coordinator on +359 89 606 0394.
Once Ukrainians get to Ruse they can travel to any Bulgarian destination by train or bus.
The trains are free of charge for Ukrainians, they only need to show their Ukrainian Passport which they have used to pass the border and they will be given a ticket for free.
Buses - there are some free of charge buses that can take Ukrainian people to Sofia or Varna. If one wants to get to another destination here is a link to a bus service which isn't free -