This story is developing and will continue to be updated.

Catholics across Europe have reacted to Russia’s invasion of Ukraine with expressions of solidarity with the Ukrainian people and prayers for peace.

"Today peace on the whole European continent and beyond is facing a serious threat," Cardinal Jean-Claude Hollerich said Feb. 24.

Hollerich, who serves as the president of the Commission of the Bishops’ Conferences of the European Union, said that he is deeply worried that the escalating Russian military actions in Ukraine have opened up "the alarming scenario of an armed conflict causing horrific human suffering, death and destruction."

The Catholic cardinal called on EU leaders to "endorse measures promoting de-escalation ... while avoiding any steps that could potentially reinforce the violent conflict."

Archbishop Stanisław Gądecki, the president of the Polish bishops’ conference, issued a condemnation of Russian President Vladimir Putin's actions in Ukraine.

“I strongly condemn the actions of Russia and Vladimir Putin as an unacceptable and shameful act of barbarism directed against sovereignty,” Gądecki said in an appeal.

“At the same time - together with the whole Church in Poland - I express my solidarity with all Ukrainians, both in Poland and in Ukraine, assuring them of our closeness, prayer and availability to help,” he said.

Bishop Kenneth Nowakowski, the Ukrainian Catholic eparchial bishop of London, urged government leaders and those in positions of power to remain steadfast in support of “the innocent citizens of Ukraine.”

“The day that we have been hoping would never come has arrived," Nowakowski said.

"This morning we woke up to hear the news that Russia has unleashed its troops into an invasion of Ukrainian soil as well as firing missiles into Ukrainian territory."

“We place the people of Ukraine under the protection of the Holy Family, our Lord and Savior Jesus Christ, the Most Holy Mother of God and ever-virgin Mary, and the holy and righteous St Joseph the Betrothed,” he said.

Tetiana Stawnychy, the president of Caritas Ukraine, a Catholic charity, expressed concern that Ukraine is heading for a humanitarian catastrophe, adding that there were already 2.9 million people on both sides of the contact line who were in need of humanitarian assistance before the attack.

"The events which began early this morning will inevitably lead to a colossal humanitarian catastrophe," Stawnychy said.

"It is impossible to believe that in the 21st century in the center of Europe people have to wake up at 5 am from explosions and the sound of air raid sirens.”

Archbishop Wojciech Polak, the primate of Poland, called Feb. 24 a “tragic morning” in a message sent to the leader of the Ukrainian Greek Catholic Church.

“On this tragic morning, joining in pain and asking God to stop the Soviet occupier, I remember in prayer and cry for peace for the beloved Ukrainian people,” Polak wrote in the text message, according to the Catholic Church in Poland.

English Cardinal Vincent Nichols underlined that dialogue and negotiation are the only way forward.

"The international community must unite in seeking an end to this conflict through peaceful means ... It is their responsibility to ensure that international law and territorial sovereignty are respected," Nichols said.

"We must also keep in mind the plight of those who will become refugees as a result of this attack."

The cardinal said that he would be offering a Mass for the intentions of the victims of the conflict and their families, adding that he was praying for the Ukrainian people's "strength and perseverance under this onslaught."

Russian military breached the border of Ukraine at several points on the morning of Feb. 24. Ukrainian officials reported shelling and missile strikes across Ukraine, including at airfields and military headquarters near Ukraine’s capital city of Kyiv.

Ukrainian officials said, as of almost 3:00 p.m. local time, that Russia had carried out 203 attacks across the country since before dawn, according to Reuters.

Both military and civilian deaths have been reported.

According to BBC News, on Thursday Russian military crossed into Ukraine not only from points on the Russian border, but also from Belarus, a Russian ally.

Bishop Oleg Butkevich, the head of the Catholic bishops’ conference of Belarus, commented that “the world was shaken by the tragic news that a military conflict has broken out between our neighboring countries.”

“I ask that, in peace, we may offer our prayers, both personal and in parish communities, for an end to the conflict as soon as possible and for the least number of victims from the conflict. And that it does not escalate into another world war,” he said.

“Christ tells us: ‘Everything is possible to one who has faith.’ (Mark 9:23-24) God help our unbelief. I also encourage fasting and offering up the sacrifice of suffering for this purpose.”

Major Archbishop Sviatoslav Shevchuk, the leader of the Ukrainian Greek Catholic Church, supported Ukraine’s right to defend its independence as Russia attacked Ukrainian military targets on Thursday morning.

“It is our natural right and sacred duty to defend our land and our people, our state and all that is dearest to us: family, language and culture, history and the spiritual world,” he said.

Ukraine is a country of 44 million people bordering Belarus, Russia, Moldova, Romania, Hungary, Slovakia, and Poland.

Shevchuk leads the Ukrainian Greek Catholic Church, the biggest of the 23 Eastern Catholic Churches in full communion with the Holy See.

Fears that Russia was beginning a full-scale invasion of Ukraine were heightened this week after Russian President Vladimir Putin announced that he would recognize the breakaway Ukrainian regions of Lugansk and Donetsk as independent entities.

The eastern regions, which are run by Russian-backed separatists, include land currently held by the Ukrainian armed forces.

“At this historic moment, the voice of our conscience calls us all as one to stand up for a free, united and independent Ukrainian State,” Shevchuk said.

“The history of the last century teaches us that all those who started world wars lost them, and the idolaters of war brought only destruction and decline to their own states and peoples.”

The Vatican’s Secretary of State Cardinal Pietro Parolin released a video message Thursday afternoon in which he said that wisdom is needed to save the world “from the folly and horrors of war.”

"And let us continue to pray and fast — we will do so next Ash Wednesday — for peace in Ukraine and throughout the whole world," Parolin said.