Protesters demanding the closure of a huge gold mine in Indonesia's Papua province have beaten to death three policemen and a soldier.
The incident will stoke tensions in the province
The incident happened on Thursday outside the university in the provincial capital, Jayapura.
There have been protests against the mine's operator - US giant Freeport McMoRan - since security forces tried to evict unlicensed miners last month.
Supporters of Papua independence see the mine as a symbol of unfair rule.
Thursday's violence happened after police moved against a group of some 500 students who had blocked a road outside the university for a second day.
The police said they tried to persuade the protestors to move and when that failed they resorted to rubber bullets, teargas and armoured vehicles to clear the blockade.
According to journalists at the scene, the crowd then cornered three policemen and beat them to death with sticks and stones.
A fourth man, reported to be a soldier or air force sergeant, was also killed. Police said a further 19 police officers were injured.
An Indonesian TV channel reported that the bodies were then burned, but this was later disputed.
"At first we thought that was the case, but no, they were all stabbed and beaten to death," police spokesman Kertono Wangsadisastra said.
Police said that by late Thursday afternoon the protestors had dispersed, taking refuge in thickly wooded mountains behind the university campus.
The incident was the most serious for several months, and was likely to stoke tensions in the province, which has seen a low-level insurgency against Indonesian rule.
The Freeport McMoRan mine - which extracts copper as well as gold - is one of the largest in the world.