Thousands of refugees, including children and babies, were left stranded at borders in the Balkans as Croatia and Slovenia and other countries began tightening border control and limiting the number of refugees allowed in their countries.

According to CNN, approximately 10,000 refugees were left stranded in Serbia due to Hungary closing down two of its borders – including its border with Serbia. Many of the refugees have been bottlenecked on Serbia’s western border where they are trying to enter Croatia, then travel to Slovenia. Slovenia recently announced they would only accept 2,500 refugees a day, but their neighbor, Croatia, is letting more than 5,000 travel through to Slovenia, despite Slovenia’s limitations. Slovenia borders Croatia, Austria, Hungary, and Italy.

“Croatia is ignoring our pleas, our plans,” Bostjan Sefic, state secretary at Slovenia’s interior ministry, told a news conference, saying the army would be called in to help if such a rate continued.

Croatia is also considering tighter restrictions after more than 200,000 refugees crossed their border over the past month. Government officials are considering raising a barrier or fence across the border.

“I would like to avoid the situation where we have to put any kind of physical barrier on the border, but I have always requested from our government a tight control of the border… I don’t know about the fence, I don’t exclude it as a possibility in the future,” said Croatian President Kolinda Grabar-Kitarovic.

U.N. refugee agencies have reported another concern: they are running out of supplies. As colder weather approaches, doctors are worried that they will not have the supplies to treat children and weaker adults who suffer from hypothermia. Aid agencies and charities continue to donate to the cause, but have been struggling to keep up with the large number of refugees fleeing war in Africa, Asia, and the Middle East.

“We don’t have a chance to treat, we don’t have the actual medicine to be given out to them, we don’t have any more rain coats,” Dr. Ramiz Momeni, London-based founder of the Humanitas Charity, told Sky News.

“There is a lack of food, lack of blankets, we are missing everything,” UN Refugee Agency spokeswoman Melita Sunjic also told the media outlet.

Since the crisis began, more than 615,000 refugees have arrived in Europe via sea so far this year. In 2014 there were 626,000 asylum applications according to Eurostat figures. Germany alone is expected to see up to 800,000 asylum seekers and refugees this year.