• Cable news network RT America, the English-language sister network to Russian news network RT, is immediately halting operations, according to a memo received by CNBC.
• More than 100 employees were notified Thursday that they will be laid off, one of the people said.
• A company memo said their employment will end on May 3, according to a source.

The U.S. cable news network RT America informed its employees that it's halting operations immediately and laying off almost all staff, according to a memo obtained by CNBC.

RT America is an English-language sister network of RT, the Russian state-owned news channel. It's operated by Russia-backed T&R Productions, which sent a memo Thursday to more than 100 employees informing them their employment will end on May 3, according to a person familiar with the matter.

"As a result of unforeseen business interruption events, T&R Productions LLC will be ceasing production and, therefore, must lay off most of its staff who work at all its locations," wrote Misha Solodovnikov, T&R Productions' General Manager, in a note to employees. "We anticipate this lay off will be permanent."

DirecTV, the largest U.S. satellite-TV operator, stopped carrying RT America earlier this week — a decision based on Russia's attack on Ukraine. Roku followed DirecTV's lead by removing the network from its Roku Channel Store.

RT America employees found out Wednesday there would be no live programming and were told by management to come back to the office at noon Thursday for more information, according to a person familiar with the matter. There was a brief meeting led by news director Mikhail Solodovnikov, who informed employees RT America was shutting down immediately, the person said.

The news caught some employees off guard. They speculated that program cutbacks could follow the actions taken by DirecTV and Roku but didn't expect a full-scale shutdown, two of the people said.

CNN first reported RT America's immediate closure.