Since the beginning of the Russian invasion of Ukraine, Poland has taken in 300,000 Ukrainian refugees, according to Warsaw Mayor Rafał Trzaskowski.

While Trzaskowski told ABC News’ Linsey Davis Tuesday that the city and its residents have welcomed these families and doing their best to accommodate their needs, they still face uphill challenges as more refugees arrive.

“We are going to welcome whoever needs help, but if a strain on the public services, schools, [and] health system [becomes] huge, the solidarity might wane in a few weeks,” the mayor told ABC News.

As the number of refugees is expected to grow while the conflict continues, Trzaskowski is calling on leaders around the world to assist with the refugee efforts.

As of March 29, over 4 million Ukrainians have fled to nearby countries to escape the war, according to data from the United Nations. Poland has taken the majority of those citizens, 2.3 million, according to the U.N.

Trzaskowski said his city’s refugee response has been “improvised” as the local government, regular citizens and organizations have come together to provide the hundreds of thousands of families with support.

Ukrainian citizens have been granted access to free education and free health care in Poland and 13,000 Ukrainian children are already attending Warsaw schools, according to the mayor.

“This is really a huge challenge also financially, but you know, we have to organize it,” Trzaskowski said.

He added that the city’s social workers are overburdened with the daunting task of registering over 300,000 people with Polish social service agencies and programs.

“So now I’m thinking how to put more people at a task of doing it as quickly as possible,” he said.

The mayor tweeted on Monday that the city’s refugee assistance efforts requires more investment and personnel and called on the European Union to offer direct support.

“We need a system because we don’t know [if] maybe we are going to have another wave of refugees in just in just a week or two. We need to be prepared,” he said.

World leaders have recently pledged to help the growing number of families who are fleeing Ukraine.

Last week, President Joe Biden announced the U.S. would accept 100,000 Ukrainian refugees, and other countries, such as Canada have promised to take them.

Trzaskowski said he is hopeful that more countries and the United Nations will step up their efforts and alleviate some of his country’s burdens, but in the meantime he pledged that his citizens will continue to welcome the refugees as one of their own.

“Ukrainians are among us but they’re with us they’re not as if relegated to the margins of the society they’re in our homes they are participating in our life and that’s that’s the beauty of it,” he said.