It was to be a no holds barred dialogue with Prime Minister Najib Abdul Razak at the Putra World Trade Centre in Kuala Lumpur and former premier Dr Mahathir Mohamad has been there since 8.50am.
But the police ordered that the event dubbed "Nothing to Hide" to be cancelled, citing security concerns. This riled up those present.
Malaysiakini brings you live coverage of the situation.
11.07am: Mahathir leaves the venue to chants of 'Hidup Tun'.
10.55am: During the Q&A session, Mahathir was asked if Najib was afraid of him, to which he replied, "I am just an ordinary man, why fear me."
To another question, Mahathir said Najib had missed the opportunity to clear the air on 1MDB.
10.50am: Mahathir, flanked by Ahmad Said and Khairuddin Abu Hassan, is giving a press conference and reiterates all that he has said about 1MDB.
10.40am: Mahathir agrees and steps down from the stage. He then asks permission to speak to the media.
10.35am: Police try to stop him from speaking and this infuriates the crowd.
10.33am: Mahathir addresses the audience.
10.37am: Organiser says police have prevented Najib from attending and negotiations are still ongoing.
The crowd, some of whom came as early as 8.30am, numbering close to 2,000 are growing restless, and music is plated to calm them.
10.32am: After waiting for Najib to turn up for about two hours, Mahathir enters the hall and is escorted by Perkasa members and chants of "Hidup Tun" ring out
10.00am: Ahmad Maslan leaves the venue.
9.54am: A small commotion erupts when a man is carted away by security personnel after he started shouting.
9.45am: Crowd swells to about 2,000.
9.20am: Mahathir is taken to the holding room.
9.15am: Several VIPs are spotted in the crowd. This includes Deputy Finance Minister Ahmad Maslan, former Terengganu menteri besar Ahmad Said, former Terengganu Umno chief Annuar Musa and Perkasa president Ibrahim Ali and several others.
9.00am: Following negotiations, the journalists were allowed access.
8.53am: IGP tweets that the event should be cancelled due to security reasons.
8.50am: Former prime minister Dr Mahathir Mohamad arrives to chants of 'Hidup Mahathir'.
8.30am: Journalists were not allowed to enter the venue.