Treasury chief Rishi Sunak and Health Secretary Sajid Javid both resigned.
At least seven people were killed, officials said.
The move further increases Russia’s strategic isolation in the wake of its invasion of neighboring Ukraine in February.
After more than four months of ferocious fighting, Russia claimed full control over one of the two provinces in Ukraine’s eastern industrial heartland.
U.S. officials said there was “no reason to believe” the shooting of Shireen Abu Akleh was intentional.
“President Zelenskyy, he gets to determine how victory is decided and when and on what terms,” Kirby told "Fox News Sunday."
Russian President Vladimir Putin declared victory one day after Ukrainian forces withdrew from their last remaining bulwark of resistance in the province.
Steve Ho, a member of Hong Kong's biggest pro-Beijing party, said he tested positive for COVID despite adhering to strict protocols ahead of Xi's arrival.
A 22-year-old Danish man was arrested after the attack, authorities said.
If confirmed, Russia’s complete seizure of Luhansk would provide its troops with a stronger base from which to press their advance in the Donbas.