Belgrade (AFP) — Thousands of protesters blocked major roads in Belgrade and other Serbian cities on Sunday, as demonstrations calling for snap elections continued into a second night following Saturday’s huge rally in the capital.

On Saturday, around 140,000 people rallied in central Belgrade, the latest gathering in over half a year of demonstrations triggered by the collapse of a train station roof in the city of Novi Sad in November, killing 16 people in a disaster widely blamed on shoddy construction resulting from entrenched corruption.

Anti-graft activists, responding to the arrest of a “large number of citizens” in the wake of the protest, called for more action - with thousands responding to set up dozens of blockades around the capital.

At the key Autokomanda junction, protesters were setting up tents preparing to stay overnight, according to an AFP photographer.

Protesters posted images of similar blockades from several other cities, including Novi Sad, and published plans for dozens of similar protests around the country.

Local media and videos posted by protesters showed large crowds streaming onto major bridges, and students forming barriers from bins and fences.

Serbian Interior Minister Ivica Dacic told local station Pink TV that authorities were monitoring the situation.

Earlier on Sunday, President Aleksandar Vucic remained defiant against protesters’ demands for early elections, accusing the student-led movement of causing “terror”

“Serbia has won, and you cannot defeat Serbia by violence as some wanted,” Vucic said in a televised speech.

Clashes with police after Saturday’s rally ended with dozens of arrests, as riot officers used tear gas and batons to attempt to disperse a crowd that also threw bottles and flares.

Authorities said 48 officers had been injured, one seriously, and put the crowd size at 36,000 — well below an independent estimate by the Archive of Public Gatherings of around 140,000.

Dacic said 22 people had sought medical help, of whom two were seriously injured.