The Independence Day clashes are the latest outbreak of violence in a country struggling with a deepening economic crisis and sometimes bloody street protests demanding a change of government.
Video from inside the building showed blood on walls and wounded lawmakers being tended to by colleagues.
At least seven legislative employees and five lawmakers have been injured, according to National Assembly President Julio Borges.
Lawmakers pledge vote will go ahead
Despite the violence, lawmakers vowed to proceed with a scheduled session to discuss a unofficial plebiscite — a move toward an election seeking to oust Maduro — National Assembly vice president and opposition leader Freddy Guevara said on state-run TV station Capitolio.
The July 16 plebiscite will pose questions on the level of confidence in Maduro and seek public input on his rewriting of the constitution.
Guevara, told CNN Español that lawmakers Armando Armas and Américo de Grazia were injured in the confrontation with Maduro loyalists. Lawmakers Nora Brancho, Luis Carlos Padilla and Leonardo Regnault were also injured, according to a Twitter post from the assembly.
Assembly member Armando Armas, his head and white-shirt bloodied, posted a video on Twitter with the message: “We were elected to defend the country. Today, July 5th, barbarity wants to impose itself before civility. Down with the dictatorship!”
“We will defend Venezuela at all costs, even with our lives,” he said in the video.
Violence follows continuing unrest
No one at the Supreme Court was injured and military forces did nothing to intervene — even though Perez was flying in plain sight. Government critics said it was a stunt orchestrated by Maduro to justify using a heavier hand on protesters. Maduro condemned the attack and denied any involvement.
This week, Perez appeared in a video saying the goal of his mission was achieved, which was to damage the building housing the Justice Ministry and Supreme court without causing collateral damage.
“We are not assassins, like you, Mr. Nicolas Maduro,” he said.
Maduro also battled last week with his attorney general, Luisa Ortega, who broke government ranks this spring and has lambasted Maduro for alleged human rights abuses. The Maduro-backed Supreme Court froze Ortega’s assets and ordered her not to leave the country as she may face a trial.
“I have committed no crime nor errors and I am not going to submit to this unconstitutional and illegitimate court,” Ortega said at a news conference Tuesday, explaining why she failed to attend a Supreme Court hearing.
Months of unrest
Opposition lawmakers were physically pushed around last week at the National Assembly by the national guard, which is controlled by Maduro.
Near daily clashes between government forces and protesters have paralyzed the country for months. More than 80 people have died since the beginning of this latest round of civil unrest, according to the attorney general’s office.
With unemployment set to surpass 25% this year and severe food shortages, some Venezuelans have opted to leave the country.
Venezuelans are also struggling with a shortage of medicine, and some are also taking the sick to Colombian hospitals.
The government has been accused of intimidating and restricting the media, taking CNN en Español off the air. It tightly controls visas for foreign journalists including CNN, arresting those who report from inside the country without proper permits.
CNN’s Julia Jones, Ana Melgar, Gisela Crespo, Nicole Chavez and Marilia Brocchetto contributed to this report.