The Iraqi army for the second time this week turned its guns on its own people as the regime in Basra tried to stop thousands of citizens from fleeing the city.
Rounds of mortar were fired into the crowds of people who had gathered at the main bridge that leads out of the city to escape desperate conditions inside the city, besieged by British forces.
Although the mortar units were engaged by elements of the 1st battalion Black Watch guarding the far bank, one British medic at the scene described seeing hundreds of dead and injured. "They were still clearing them away as night fell," he said.
The mortar attack happened only a few days after a brief uprising in Basra had provoked 15 minutes of intense artillery fire within the city as the regime fought to remain in power.
The strategy shown by the Iraqi army and militia groups which patrol the streets has been to keep as many civilians inside the city in order to discourage an allied attack.
Last night, however, British forces were put on standby to enter Basra should a more serious revolt take place.
British forces have also moved across the Shatt al-Basra - the waterway which divides Basra from allied-occupied Iraq - at three strategic points along its eastern shore as the noose is tightened around the city.
"We're getting into position and we hope that the people in Basra see what we are doing and understand that we shall be here to help them should a serious effort be made to change the regime," a senior British officer said.
Over the past 48 hours military intelligence has reported that the experienced Iraqi 6th armoured division, which fought in the Iran-Iraq war, has mobilized and is moving southwards from positions on the Euphrates river in order to relieve the siege.
Throughout the early hours of the morning advance reconnaissance unit belonging to the Queen's Dragoon Guards have been engaging with enemy targets to the north of the city.
The ground rocked to the sound of fire from two Challenger 2 tanks as they chased Iraqi armoured personnel carriers through the streets of the small village of Gul Ashab, a few kilometres to the north of Basra.
Should the 6th armoured division be successfully halted, British units then plan to push north along the border with Iran to open an eastern flank on the push to Baghdad.
"We intend being in Baghdad before the Americans," Major Matthew Botsford, of the Queen's Dragoon Guards, said.