Birds scattered from amid the ornate balconies and beautifully decorated tile arches of the courtyard surrounding the holy shrine of Imam Ali.
A mortar round had landed close by and the sound of the explosion echoed around the perfect golden dome of one of Shia Islam's holiest sites.
Sadr supporters say they will continue to defend the shrine
In contrast, the hundreds of people lying in the shade or gathering in groups chanting and singing, hardly noticed.
They are used to the sounds of battle - the fight for Najaf has been going on for days and American air bombardment here has been among the heaviest since the end of the war.
But there appear to be no guns inside the sacred courtyard - even if the narrow streets and alleyways surrounding the mausoleum are protected by militia armed with rocket launchers and automatic weapons.
A main road marks the end of American control and the start of the snipers and defensive positions of the Mehdi Army.
We crossed it with caution, arms raised in surrender - a white T-shirt acting as a flag in front.
The American tank appeared to ignore us; the armed supporters of Moqtada Sadr welcomed us as we picked our way through broken glass and debris, shrapnel and bullet holes peppering the street.
Fighters welcomed journalists into the shrine
The men seemed in good spirits, one who saw the camera immediately pulled his ammunition belt across his chest and lifted his gun in the air - the other hand gestured a victory sign.
They joked with us - "Have you got your press passes?" one said. "Because if the Iraqi police are in the shrine you will have to show them or you'll be arrested."
He burst into laughter - the government gave a statement saying the shrine was in the hands of the police and that 400 fighters had been arrested.
It was clear the only people controlling the streets of Najaf's old city were the heavily armed supporters of Mr Sadr, the young cleric who has helped plunge the interim government deep into crisis only weeks after it assumed control of the country.
The silence of the stand-off is broken by sniper fire, and the rattle of machine guns in the holy place that is now a war zone.
The stand-off appears to be going nowhere.
All the final warnings from the interim government have come to nothing - contradiction, broken promises and empty threats have characterised this crisis.
It is not going to be an easy stalemate to crack
Moqtada Sadr's spokesman in the shrine said control would be passed on to the higher Shia religious authority - a possible chance for a settlement.
But then he added the Mehdi Army would stay on the streets outside the courtyard to protect the holy city - not what the government demanded.
And so the interim government, committed to action but afraid to damage the Imam Ali shrine, is losing credibility.
The interior ministry was at the very least wishfully thinking, at the worst lying, when it issued its statement over control of the shrine.
Mr Sadr, wherever he might be, also needs to come out of this appearing not to have backed down.
It is not going to be an easy stalemate to crack.
What happens next is not a question that can be answered by those who call themselves "human shields" in the shrine courtyard.
They continue to pray for peace as war rages on around them.