TEHRAN - A few days ago Tehran's most famous boulevard was alive with joy and celebration as supporters of moderate presidential candidate Mirhossein Mousavi vented their desire for social and political change in Iran.
Last night, tree-lined Vali-ye Asr avenue had turned into a smouldering battle-zone after widespread clashes sparked by his election defeat to hardline President Mahmoud Ahmadinejad, an outcome which Mousavi denounced as a dangerous charade.
The long artery in which boisterous pro-Mousavi crowds had descended nightly in the run-up to Friday's poll was now taken over by riot police wielding batons against thousands of protesters accusing the government of stealing the vote.
Shattered glass and small fires testified to the mayhem unleashed after the Interior Ministry declared on Saturday that Ahmadinejad had won a landslide against his reformist rival.
Iranian officials reject opposition charges that the vote was rigged. Ahmadinejad termed the election free and healthy.
Swarms of police on motorbikes sped past as I walked up Vali-ye Asr towards my home in relatively affluent northern Tehran, hitting cars which happened to block their way.
I received two blows myself as I walked past a column of police on foot near Vanak Square, where taunting anti-Ahmadinejad demonstrators had thrown stones at them earlier in the day.
Elsewhere in the capital of 12 million, a colleague saw police beating up young men with truncheons and, in another location, firing warning shots in a post-election crackdown.
Virtually every bus stop on my route home around midnight had been wrecked, forcing me and the few other pedestrians around to manoeuvre through thick layers of glass shards.
Several bank windows were smashed and street signs ripped up or bent. People were standing silently at street corners gazing at the aftermath of clashes in a normally orderly city.
A WAR? NO, AN ELECTION
Earlier in the day in the same street, I saw hundreds of Mousavi supporters protesting at the election result: Mousavi take back our vote! What happened to our vote? they chanted.
Reza, a 25-year-old student who only gave his last name, told me: The election was corrupt. If Ahmadinejad had won where are his supporters? How come they are not celebrating?
A few hours later the demonstrators were gone and truckloads of police drove by, making clear who was in charge.
Tehran deputy police chief Mohsen Khancharli had warned that his men would strongly confront any unauthorised gathering, in comments carried on Saturday by the official IRNA news agency.
On the eve of the election, gleeful Mousavi fans draped in his green campaign colours danced, shouted and honked horns in Vali-ye Asr in scenes unseen since a wave of popular support swept reformist Mohammad Khatami to power in a 1997 vote.
Now members of the religious Basij militia and other Ahmadinejad backers had the upper hand, driving up and down the same street. Some were wrapped in the red, white and green Iranian flag, the symbol of the incumbent's campaign.
At the Parkway roundabout, riot police stood at the roadside or rested on the pavement. Stones and rocks littered the street. Colleagues helped an injured policeman to a nearby ambulance.
Jang bud (Was there a war)? I asked a young, tired-looking policeman standing with his helmet in his hands.
Na, entekhabat (No, there was an election), he replied, shrugging his shoulders.