Louise Williams, Jakarta – From the top of a pedestrian overpass that straddles the chaos raging across the 12-lane highway in central Jakarta, there is a clear view to a kill.

In the confusion of the fighting between students and police on Tuesday night, which cut this main artery to the airport, there was only the terrifying crack of gunfire – rubber bullets indistinguishable from live rounds.

But yesterday morning – as thousands of students and bystanders poured across the same bridge, the traffic held back by black-clad riot troops, the air spinning with tear gas, a petrol station and vehicles alight – the source of the fatal shots that killed five student protesters seemed clearer.

On the campus and in the streets around the elite Trisakti University, where the five young men died on Tuesday, lay the spent cartridges of live, "sharp" bullets which appeared to have been fired into the university from the bridge.

In no assessment of the deadly face-off between security forces and students that has been raging in Jakarta is it possible to interpret this action as part of the rules of engagement of the Indonesian police or soldiers.

Said one diplomat yesterday: "Sharp rounds are for self-defence only, to be used if a fellow officer is in danger or if a crowd invades a military installation.

"The campus is a safe area; the military has already said that students are permitted to protest inside."

But it appears that the five young, unarmed students were shot dead as they fled, attempting to seek sanctuary inside their university.

Scores more were injured, and by yesterday afternoon a new battle was raging between those who had come to mourn and those who would not let the funeral parade pass.

Yesterday, as thousands cheered and clapped speakers condemning the action of the Indonesian security forces, hundreds of trucks and buses from other universities poured in bringing young people carrying black banners and wreaths.

But soon it all went wrong. The riot troops again closed the main road and the confusion of another street battle erupted - trucks set on fire, a petrol station alight and thousands fleeing as the air cracked with the sound of gunfire and tear gas canisters.

The official version of Tuesday's events, as told to Western embassies, was that the harsh crackdown against the unarmed students was undertaken because students had attacked and beaten a military intelligence officer.

But I know that is not true, because I was standing only metres away from the confronting forces when the military attacked.

First, the ranks of the riot troops parted and a black tear-gas cannon mounted on a tank moved forward and the students fled.

But no tear gas was fired; instead the riot troops chased the students with guns.

It is not clear when the rubber bullets were substituted with live rounds, but it is abundantly clear that either tear gas or a water cannon could have easily cleared the crowd and prevented the deaths and injuries among the students.