The students held a demonstration from the Chichiri campus through Chipembere highway to the main campus.
MBC Online understands that the students were demonstrating against lack of proper security at their Chichiri hostels where armed robbers Monday night stole over 30 laptops, phones and other items.
They wanted the university management to intervene by changing security guards.
The police at the nearby southern region headquarters got into action to stop the demos and started firing rounds and rounds of teargas at the protesting students.
The Chipembere Highway was closed for an hour, around lunch time, leading to congestion along Kamuzu Stadium and BAT road.
The firing of teargas continued, as police officers and staff at the nearby MBC headquarters, fled from their offices to seek relief in open spaces from eye and nose stinging teargas.
It is not known as to who torched the hostel as some students were seen retrieving property which was damaged from the inferno as fire engine from Blantyre City Council rushed to douse the fire.
MBC Online failed to get immediate comments from both the Police south regional headquarters and Poly management.
Poly students are often involved in crushes with police over personal grievances and school issues.