Russia-Ukraine updates: Putin says 'certain positive movements' in negotiations

Joey and Paula Reed, the parents of ex-Marine Trevor Reed who has been held in a Russian prison for over two years, said they are more fearful for their son's life after he called them from Russia.

The couple said in statement that Reed is "seriously ill" and was "coughing up blood multiple times a day, [and] running a fever."

"He also reports a broken rib because 'something fell' on him,' and to make matters worse, he's being underfed," the Reeds said.

During the call, Trevor Reed was sent to the "prison disciplinary ‘commission,'" according to his parents, who added they feared he was being sent to solitary confinement.

The couple recently spoke with President Joe Biden about their son's imprisonment.

"We were able to tell him [we] spoke to President Biden and anxiously await hearing from the White House as the President promised. Trevor increasingly feels left behind, and it’s heartbreaking for us to hear that from our son, whose service we are so proud of," they said.

-ABC News' Conor Finnegan

Russian troops have advanced about 3 miles toward Kyiv in the past day, bringing them within roughly 9 miles of the city center, according to a senior U.S. defense official.

The troops are to the northwest of Kyiv, in the area of the Hostomel Airport, which is about 5 miles from the outer city limits.

Two lines of advance from the northeast are also making progress on their push to Kyiv. The closest of these troops is now approximately 25 miles from the heart of the city, the official told reporters during a Thursday evening briefing.

Some troops from one of those lines of advance, emanating from above the town of Sumy, seem to have turned around, heading back northeast, though the reason for the about-face is unclear, the official said.

Kyiv remains "well-defended" by Ukrainian forces, the official said. Security assistance continues to flow into Ukraine, including air-defense systems, according to the official.

Since the start of the invasion, Russian forces have fired more than 775 missiles against Ukraine, the official said.

-ABC News' Matt Seyler

Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, spoke with his military counterparts in France, Poland, Romania and Bulgaria Thursday about the latest developments in Ukraine, according to the Pentagon.

While the Pentagon didn't provide many details about his discussions with the military leaders, it said they shared assessments and intelligence.

Milley also discussed the recent deployment of U.S. military forces to Poland and Romania with their respective military leaders, according to the Pentagon.

-ABC News' Luis Martinez

While tens of thousands of Ukrainians were able to flee the country via humanitarian corridors on Thursday, those still in Mariupol have not been able to leave, as the city is under total siege by Russian forces.

A second attempt for residents to leave on Thursday was abandoned as the Russian military continued to bombard the Mariupol and the humanitarian passages surrounding it, Ukrainian President Volodymyr Zelenskyy said during a press briefing Thursday.

About 300,000 are suffering from lack of water, power and food, said Iryna Vereshchuk, a vice prime minister helping oversee the evacuations. Russia also destroyed and mined surrounding cities, Vereshchuk said.

Albert Khomyak, who lived in Mariupol's eastern outskirts, told ABC News that Russian troops have now entered their street.

"They are trying to destroy Mariupol, that way to destroy the resistance," he said.

Khomyak was somehow able to drive with his family in their own car out of the city, he said.

About 16,000 people are estimated to have evacuated Ukraine on Thursday now that the corridors near the northern Sumy region and some of the towns just northwest of Kyiv have been firmed up, Russian officials said.

But the ceasefires that allow these evacuations are temporary and very imperfect, and sporadic firing still happens throughout them.

The ceasefires then end at 9 p.m., when full-scale offensive attacks from Russia begin again.

-ABC News' Fidel Pavlenko and Natalie Vikhrov