Pandemonium broke out after chairs were thrown and shoes flung on stage as former prime minister Tun Dr Mahathir Mohamad was speaking at the Nothing to Hide 2.0 forum today.
The former prime minister was not hit by the slipper or injured in the incident.
The town hall meeting was aimed at highlighting a major financial scandal that has ensnared Prime Minister Najib Razak, and which has spurred Mahathir, 92, into coming out of retirement to take on his ex-protege. One of them was a college student from Shah Alam.
As more joined in the fracas and a brawl ensued, some of the assailants began lighting up flares and one was seen flying across the hall just before the stage where the PPBM chairman was at.
Mahathir, who had been taking questions from the audience when the violence erupted, was escorted from the building and was unhurt, Syed Saddiq said.
The two men were apprehended by the organisers, the Parti Pribumi Bersatu Malaysia Armada youth wing, before they were handed over to the police.
"It is clear it was created to silence Mahathir and the opposition", said Syed Saddiq, the youth chief of Mahathir's recently established Bersatu party. If we want to delve in old issues, we can never unite. "It's a cowardly act".
It was not clear who was behind the violence but it illustrates that political tensions are rising before elections which Najib must call by mid-2018, and that Mahathir is viewed as a potent threat.
Mahathir, who was premier from 1981 to 2003, has excoriated Najib over allegations billions were looted from state investment fund 1MDB in an audacious campaign of fraud and money-laundering. The Sunday event - dubbed "nothing to hide" - would have included the debate, but Najib wasn't expected to show up and did not appear. Najib has denied any wrongdoing.
In fact, Tun Mahathir has set aside his past with Anwar.