RIO DE JANEIRO — Brazilian police arrested 10 people who allegedly pledged allegiance to the Islamic State group on social media and discussed possible attacks during the Summer Olympics, officials said Thursday.

Justice Minister Alexandre de Moraes said in Brasilia, the capital, that 10 suspects had been detained and two more were being sought. All are Brazilian, and one is a minor.

Police acted because the group discussed using weapons and guerrilla tactics to potentially launch an attack at the Olympics, which begin Aug. 5, he said.

However “they were complete amateurs and ill-prepared” to actually launch an attack, Moraes said. “A few days ago they said they should start practicing martial arts, for example.”

The arrests were made in 10 different states, including Sao Paulo and Parana in the southern part of the country, and it was not clear whether the suspects knew each other beyond their online contacts.

Moraes said there were no specific targets for an attack.

Moraes said they had all been “baptized” as Islamic State sympathizers online and none had traveled to Syria or Iraq, the group's stronghold, or received any training. Several were allegedly trying to secure financing from the group, known by the acronyms ISIS.

The justice minister said one of the suspects communicated with a store in Paraguay via email in an alleged attempt to by an AK-47 assault rifle.

Brazilians are allowed to possess small firearms but must have a license and training. Only members of the military may possess assault weapons, although firearms are common in slums controlled by drug gangs.

Moraes said authorities seized computers, cellphones and other equipment, but no weapons.