Another five people were also arrested in the early hours of Tuesday during a police raid on the representative's house in westRio where they were having a meeting.
They tried to resist arrest and shot at police who were laying siege to the house. The group was found with a rifle, a submachinegun, two shotguns, six pistols and three revolvers. Seven others managed to escape, said police.
All the six arrested, including Guimaraes, were charged with attempted murder, illegal possession of guns and criminal associations. They were also charged with aiding and abetting for one of them was a murder suspect at large.
The militia groups in Rio often consist of former or current police and fire brigade officers who force the drug dealers out ofthe shantytowns, take their place and extort the local residents.
Guimaraes' brother Jerominho Guimaraes, a former Rio City councilman, is also in jail currently for heading militia groups.
Rio de Janeiro state's House of Representatives will decide on Wednesday whether Guimaraes should stay in prison. The House has the power to release Guimaraes from prison, as his status as a state representative gives him immunity from prosecution.
