South Africa's parliament descended into chaos as leftist MPs scuffled with security during a key annual speech by President Jacob Zuma.
The Economic Freedom Fighters (EFF), led by Julius Malema, repeatedly interrupted Mr Zuma, demanding answers over a spending scandal.
The speaker of parliament then ordered their removal, prompting scuffles.
The largest opposition party, the Democratic Alliance, walked out in protest at their expulsion.
"You can't send police into parliament," said Democratic Alliance parliamentary leader Mmusi Maimane.
The EFF used President Zuma's annual State of the Nation speech to question him about a state-funded, multi-million dollar upgrade to his private residence.
They were evicted by large numbers of security guards. Among those thrown out was Mr Malema.
At the scene: Andrew Harding, BBC News
It began rather politely - an EFF MP standing up to interrupt President Zuma about one minute after he had launched into the substance of his State of the Nation address.
The speaker of parliament, Baleka Mbete, was expecting it, and urged the MP, and others who followed suit, to leave their questions for another occasion.
But when Julius Malema loudly demanded the president "pay back the money" from the upgrade to his home, the speaker ordered him to leave.
Malema refused, and suddenly several dozen white-shirted security officials were pouring into the room. They crowded around the EFF and began to pull the MPs out of the chamber.
I saw one MP try to swing a punch, and another threw his red hard hat at the officials. There were more scuffles and loud shouts. Shirts were torn.
Within a few minutes all the EFF MPs had been removed from parliament and the ANC majority began cheering in their seats.
Mr Malema defended his MPs' actions, calling it a legitimate attempt to defend democracy, adding that seven of his party had been injured and would be pressing charges.
It is not clear whether the guards were police or parliamentary officials: an important distinction, according to one MP, who said the use of police would be a way of intimidating the opposition.
Mr Malema and Mr Zuma were once close allies but the pair fell out.
The EFF has shaken up South African politics with a series of populist proposals to redistribute wealth.
EFF MPs accuse Mr Zuma of benefitting unduly from taxpayer-funded upgrades to his private residence in the village of Nkandla and they wanted Mr Zuma to answer questions about this before making his state of the nation speech.
Last year an independent inquiry found the president had "unduly benefited" from the expensive upgrades, which included a pool and a cattle enclosure and cost about $23m (£13.8m).
The president has denied any wrongdoing.
Despite criticism of the Nkandla upgrade and the country's stagnant economy, Mr Zuma's African National Congress was overwhelmingly re-elected last year.