Hong Kong Police Surround University, Block 800

Polytechtic University, which has been occupied by protesters since last week, has become the arena of the longest and most tense clash between police and protesters in more than five months of uprising.

Hundreds of people remained surrounded by police Monday morning, following last night's clashes, during which protesters used spears and gasoline bombs, while police threatened to use real weapons.

When a group of protesters tried to escape campus on Monday, police threw tear gas at several exits, unable to evacuate them. When another group tried to leave later, the police threw even more tear gas and used a truck with water. Several protesters were arrested on this occasion.

Police had earlier issued a statement asking protesters to drop their weapons, remove masks and leave campus, but they apparently refused to comply with this request, writes The Guardian<18x1>.