David Beasley, executive director of the UN World Food Programme, is sounding the alarm about a global food shortage for the world’s most vulnerable populations if the war in Ukraine doesn’t end soon.

“You're talking about the breadbasket of the world where we buy 50% of our grain from Ukraine. And so with the farmers on the battlefront, when it's harvest time and planting time, it's going to wreak havoc not just inside Ukraine, but worldwide,” Beasley told ABC News.

Before the war broke out, Beasley said climate, the pandemic and supply chain issues had already increased costs by millions, reduced available food and forced the WFP to cut distribution around the world.

“In the next nine months, if we don't end this war quickly, it could be hell on Earth,” Beasley said.

-ABC News' Martha Raddatz, Sam Sweeney

Fox News cameraman Pierre Zakrzewski has been killed in Ukraine, according to Fox News.

Zakrzewski, 55, was newsgathering with correspondent Benjamin Hall on Monday in Horenka, outside of Kyiv, when their vehicle was hit by incoming fire, the network said.

Hall was injured and hospitalized in unknown condition.

"Pierre jumped in to help out with all sorts of roles in the field - photographer, engineer, editor and producer and he did it all under immense pressure and with tremendous skill," a statement from Fox News PR said. "He was a professional, he was a journalist, and he was a friend. We here at the Fox News Channel want to offer our deepest condolences to Pierre’s wife, Michelle, and his entire family."

Ukrainian producer and fixer, 24-year-old Oleksandra Kuvshynova, who was working for Fox News during the war, was also killed in the shelling, according to the United Nations Educational, Scientific and Cultural Organization.

Kuvshynova was described by her colleagues as "hard-working, funny, kind and brave."

"Her dream was to connect with people around the world and tell their stories and she fulfilled that through her journalism," Fox News CEO Suzanne Scott said in a statement on her death sent to staff Tuesday.

Over 3 million refugees have now fled Ukraine, according to Filippo Grandi, the United Nations High Commissioner for Refugees.

Over 1.5 million of those refugees are children, according to UNICEF spokesperson James Elder.

NATO leaders will meet on March 24 to address the Russian invasion, NATO's "strong support for Ukraine, and further strengthening NATO's deterrence and defence," NATO Secretary-General Jens Stoltenberg tweeted.

President Joe Biden will travel to Brussels next week to attend the NATO leaders summit, White House press secretary Jen Psaki said Tuesday.

"He will also join a scheduled European Council summit to discuss our shared concerns about Ukraine, including transatlantic efforts to impose economic costs on Russia, provide humanitarian support to those affected by the violence and address other challenges related to the conflict," Psaki said.

-ABC News' Conor Finnegan