The deaths of 42 people in Odessa that greatly added to the toll of Ukraine's crisis had its roots not only in the worsening political confrontation but also rampant football hooliganism.
The clashes that culminated in a horrific inferno of a trade union building that killed 38 people - most of them pro-Russian activists - began Friday with what was meant to be a peaceful march to a football stadium for a 5:00 p.m. match.
Supporters of Odessa's home team, the Chornomorets, joined up with those of the visiting Metalist side, from Ukraine's northeast city of Kharkiv, to head to the game together.
Originally there were no plans to have the 1,500-strong march turn into what it became: a rally calling for Ukrainian unity. But that's what happened.
"It was some of the young supporters - and in this country it's the young who are naturally more in favor of a united Ukraine than backing Russia," said Natalia Petropavlovska, a leader of the local pro-Maidan movement behind the protests that drove out Ukraine's previous Kremlin-friendly government.
The march, draped in the yellow and blue of both Ukraine's national flag and the club colours of Metalist, was set upon by several hundred pro-Russian thugs obviously prepared for violence, some armed and wearing ski masks and helmets, witnesses said.
In the melee that ensued, at least four people died from gunshots and a dozen people were wounded.
Pro-Russian attack a 'big mistake'
Oleg Konstantinov was among the injured taken to the city's Jewish Hospital, where he was treated to bullet wounds to his arm and leg.
"When the shooting started, I said that maybe there were guns because the police had arrived," he said. "I was wounded in the arm, and when my friends were getting me out I was again wounded in the arm and in the leg."
An eyewitness, a 40-year-old man who gave only his first name, Bogdan, said: "The two groups of fans were marching in the city when there was shooting and also some homemade grenades thrown.
"The police did nothing. But the fans fought back. There were more of them than the attackers, and they are no strangers to brawls."
Petropavlovska said that, although the pro-Russians were armed, "they made a big mistake taking on the supporters".
"They were a big crowd and knew how to handle themselves. Not only were they not afraid of the weapons, but they became enraged when they were shot at and beaten," she said.
Information of the clash spread nearly instantly by mobile telephone and social networks, bringing more football fans to the scene.
"I was watching the match and we all noticed that at half-time the stands were emptying," said one man who was in the stadium. "They had gone to fight."
After the street clash subsided, the growing crowd of supporters turned to a tent camp the pro-Russian activists had been staying in since mid-March, on a big square in front of a trade union building.
"It was a furious crowd thirsting for vengeance that descended on Kulikove Pole place. They wanted to do away with the pro-Russian camp," Petropavlovska said. "They set about destroying it, setting it on fire."
The outnumbered pro-Russians "could have just left - they knew the angry crowd was coming, there was two hours between the attack on the march and the arrival of the supporters and our people," she said.
"But instead of that, they chose to take cover in the trade union building."
The protest leader admitted that Molotov cocktails were then thrown at the imposing stone building, as many videos posted online showed.
But the pro-Russians inside were also throwing masonry and shooting at the crowd from the roof, she said, a claim Ukraine's government confirmed.
It will probably never be established with certainty which side started the killer blaze that gutted the building, trapping the pro-Russians in a chaos of flames and choking smoke.
But many who witnessed the tragedy said firemen reacted much too slowly to save those inside.
"It's horrible. We never wanted that to happen. We are sorry these deaths happened," said Petropavlovska.
"Youths had been manipulated. I myself called the firefighters many times, and I really can't understand even now why they took so long to respond."
Ukraine declared two days of mourning in the wake of the tragedy.
On Sunday, Prime Minister Arseniy Yatsenyuk visited the grief-stricken Black Sea port city of one million inhabitants to show government's shock and solidarity.
In an interview with the BBC, Yatsenyuk vowed a "full, comprehensive and independent investigation" into the deadly events.
He also said that, while pro-Russian activists provoked the violence, a probe had been started against every Odessa police officer for their service's "inefficient" response as the rioting got out of hand.
"They violated the law," he said.
Arutz Sheva Staff contributed to this report.