How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

In the early evening of Sept. 14, around 45 cars crossed the highways of Austria, heading toward Hungary. As they approached the border, near the Austrian town of Mönchhof, they began to see people walking toward them along the motorway, illuminated under the rain by passing headlights. The motorists stopped on the road, and opened their car doors.

Coming from Vienna, Prague, and Leipzig, these drivers were on a mission to help undocumented migrants complete the final leg of an arduous journey to northern Europe.

At least four convoys this week have already made the round-trip from Austria to Hungary and back. Some, like this one, were destined for Győr, where there is a refugee camp and a migrant detention center. Some were bound for Röszke, a town on the Serbian border. Others stopped at capital city Budapest, where the temporary halt of trains bound for the Austrian border has turned the main station into a makeshift refugee camp and an epicenter of Europe’s migrant crisis.

Angelika Hofir, 54, from Vienna, Austria, drove to Budapest last week. Inspired to act after hearing rumors that the buses carrying migrants to the Austro-Hungarian border would stop running, Hofir answered a call to action on Facebook. “I don’t understand why people don’t open museums, churches and hotels for the refugees,” Hofir told Quartz.

On September 6, at Budapest’s Keleti train station, she found a group of five: two single men, one woman and her two children, all Syrian. They accepted her offer of a ride to Vienna, but then backed out—they were part of a larger group of about ten people, and didn’t want to run the risk of being separated. Quickly enough, Hofir found a second group, a family from the Syrian city of Homs with three small children.

The father, Ward Al-Alaby, a former teacher of Arabic in an elementary school in Syria, told Quartz that his family had left Syria in the beginning of August, crossed to Turkey, then taken a dinghy to Greece. They continued into Macedonia, Serbia and Hungary, and were aiming for Germany. “I know of a lot Syrians living there and I know I can find work for myself and freedom for my children in Germany,” said Al-Alaby.

Later that night, the convoy crossed back into Austria toward Vienna.

Around 330 vehicles have moved an estimated 900 refugees from Hungary to Vienna this week, according to a convoy organizer contacted via Facebook, who chose to remain anonymous. Volunteers drivers coordinate their activities through social platforms like Whatsapp, Twitter and Facebook, using hashtags including #RefugeeConvoy, #ConvoyofHope and #CarsofHope.

In the first six months of 2015, 68,000 people landed illegally in Greece, already 18,000 more than during the whole of 2014. From there, many migrants and refugees travel with buses, trains, taxis and even by foot, crossing the Balkans to arrive in Hungary, which offers land access to the 26-country free-travel Schengen Area.

In June, the Hungarian government announced it would start building a 4-meter high, 175 kilometer-long razor-wire fence along its border with Serbia, the main point of entrance for migrants crossing the Balkans. On Sept. 3, prime minister Viktor Orbán told Reuters he was ready to construct a barrier on the border with Croatia, if migrants began entering Hungary from that neighbor country. He also said, according to the news agency, that Hungary does not want a “large number of Muslim people.“

Orbán, who belongs to the conservative party Fidesz, has been drawing criticism from activists, humanitarian agencies and even fellow European leaders for his statements on migrants.

On Tuesday (Sept. 15), new laws came into effect in Hungary that make illegally crossing the border or damaging the border wall criminal offenses.

Follow Luiz on Twitter at @luizromero.