A shaky truce crumbled Thursday as gunfire erupted at Independence Square, the center of anti-government protests and an increasingly violent crisis that protest leaders say left as many as 128 dead in recent days.
At least 100 people have died and 500 have been injured since Thursday morning, the head of the protesters' medical service told CNN.
The Ukrainian government has not released an updated figure, but the interior ministry said earlier that one police officer was among the dead.
It's unclear what prompted the gunfire just hours after the government declared a truce. But CNN crews at the scene reported that as security forces were moving away from the area, a group of protesters pursued them, throwing rocks and Molotov cocktails.
"Protesters broke the truce," said a statement from President Viktor Yanukovych's office."The opposition used the negotiation period to buy time, to mobilize and get weapons to protesters."
When the bullets flew, several demonstrators fell to the ground.
Protesters grabbed the wounded by their clothes or limbs, and carried many of them to a hotel lobby at one end of the square that had been converted into a triage center.
Bodies, covered in bloodied sheets, lay on the floor. Orthodox priests prayed over them.
Protest medical volunteer Olga Bogomolets accused government forces of shooting to kill, saying she had treated 13 people she believed had been targeted by "professional snipers."
"They were shot directly to their hearts, their brain and to their neck," she said. "They didn't give any chance to doctors, for us, to save lives."
CNN could not independently confirm Bogomolets' claim of sniper fire.
On Tuesday, 28 people -- protesters and police -- were killed, officials said.
If Thursday's death toll is confirmed, it would make it the deadliest day of the protests, which began in November when Yanukovych reversed a decision to sign a trade deal with the European Union and instead turned toward Russia.