The deployments -- the first test of new President Jair Bolsonaro's tough-on-crime policies -- will grow to around 500 strong, the news reports said.

Three hundred and thirty troops had already moved into the city of Fortaleza, Ceara's state capital, over the weekend but the attacks have continued, especially in other towns.

Scores of attacks have been reported across the state over the past week.

Security videos have captured criminals torching buses, service stations, banks and shops. Explosions damaged a pillar holding up a flyover road, and punched a hole in a bridge near Fortaleza.

More than 160 people have been arrested according to state governor Camilo Santana, the G1 news website reported.

The state's security chief, Andre Costa, said gangs were responding to a crackdown on prisons by a new penitentiary director, who has ordered the confiscation of cellphones from inmates. The gangs also objected to prison transfers.

G1 reported that 100 extra soldiers had arrived on Tuesday and another 100 were on their way.

The government news agency Agencia Brasil said intelligence officers sent from other states were among the first reinforcements.

The troops are from an elite federal security force that falls under the Justice Department and which combines paramilitary tactics and weapons with police powers.

The force can be called up at the request of state governors to back up overwhelmed state police.

Brazil is one of the most violent countries on the planet. In 2017, it recorded nearly 64,000 murders, and muggings and other street crime are common.

Gangs seeking to control poor urban areas and the drug trade are heavily armed and frequently engage in fierce firefights with police.

Bolsonaro, a 63-year-old former paratrooper and veteran lawmaker, took office on New Year's Day on promises to curb crime.

His proposals include allowing "good" citizens to arm themselves to challenge criminals, and to give greater immunity to police and soldiers using lethal force.

He has an ally in the governor of Rio de Janeiro, Wilson Witzel, who has proposed allowing police snipers to kill any armed suspect, even if they are not threatening anyone, and for Brazil to open its own Guantanamo-style extrajudicial prison for criminals deemed to be "terrorists."