A forum led by Malaysia's ex-leader Mahathir Mohamad, who is seeking to oust the government, descended into violence Sunday as participants threw shoes and chairs and set off flares.
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.
But about 90 minutes into the event in Shah Alam, on the outskirts of Kuala Lumpur, troublemakers started throwing shoes, chairs and bottles towards Mahathir, organiser Syed Saddiq Syed Abdul Rahman told AFP.
They also set off flares during the short outburst of violence in the community hall where the event took place, with video footage showing the room filling with smoke.
Mahathir, who had been taking questions from the audience when the violence erupted, was escorted from the building and was unhurt, Syed Saddiq said. At least two people were injured, he added.
"It is clear it was designed to silence Mahathir and the opposition," said Syed Saddiq, the youth chief of Mahathir's recently established Bersatu party.
"But we will never be cowed by these cowards."
Senior opposition figure Azmin Ali accused Najib of "using gangsterism to silence Mahathir. This is 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.
Before the violence erupted at Sunday's event, called "Nothing to Hide" and attended by some 2,000 people, Mahathir had repeated his criticisms of Najib over 1MDB.
Najib, whose United Malays National Organisation has been in power at the head of a coalition since independence in 1957, and 1MDB deny wrongdoing.
Mahathir's party has joined the opposition coalition Pakatan Harapan, or Alliance of Hope. It last month announced a new leadership line-up, with Mahathir as chairman and his former rival Anwar Ibrahim -- who is in jail -- as overall leader.