I'd heard the sirens as I was paying at the cash till. It was only when I got outside my local supermarket that I realised the police were actually shutting down the main road through Copacabana.
The word from bystanders was that there'd been a shooting at the favela two blocks from where I live. It was pacified a few years ago - meaning the armed drugs gangs were forced out. But since November they'd been back - and causing trouble.
Only last month I was woken at dawn by the sound of military police helicopters circling the hillside community. Then I'd arrived on the scene to see armed police in pick-up trucks …. but otherwise it seemed a normal rush hour with workers wandering down to catch buses.
Last night was different - the Cantagalo area was anything but normal. Broken glass, bloodstains, burning barricades and a large crowd of angry people. People had taken to the streets in protest at the death of a local dancer who'd been found dead.
It is 10 months since a man from another favela nearby was tortured and "disappeared" by police (some officers are now in court in connection with this) - last night fingers were being pointed and parallels being drawn. Police say they're investigating the dancer's death but that his injuries are consistent with a fall.
But during the demonstration over his death another man was shot and killed - local media say police mistook him for a member of a drugs gang.
And for football fans and tourists all this chaos matters. It happened slap bang in the middle of the hotel zone and near to the fan fest (the rallying point for those who don't have a match ticket). There are traffickers with guns in the area - and heavily armed police who do not hesitate to use their weapons against them.
The chances of fans being caught up in gun violence? Slim - especially as troops are being drafted in to keep order during the World Cup. And the simple (albeit unpalatable) fact is that police wouldn't dream of treating foreigners in the way that many Brazilians in poor communities complain of.