About 100 inmates have been killed in riots in prisons in northern Brazil so far in 2017.

The violence has been caused by a feud between rival drug gangs and exacerbated by overcrowding, underfunding and corruption.

The recent incidence of violence began with a riot on January 1, that left 56 inmates dead in the northern state of Amazonas.

Then on January 6, in the neighboring state of Roraima, 33 prisoners were killed, many with their heart and intestines ripped out.

Between January 2-9, another 10 inmates were killed in smaller prison clashes in Amazonas and the northeastern state of Paraiba.

More than 100 inmates are still on the run after breaking out, which concerns locals.

"When we go out shopping, we are always aware and afraid," Manaus resident Cristiane de Araujo told Al Jazeera. ."With the children, we are always worried. We don't leave them alone any more."

More than 600,000 prisoners fill jails built for fewer than 400,000, with 40 percent of them still awaiting trial. The prison population has risen sharply since 2000, when 233,000 people were incarcerated.

Corruption is rife, allowing weapons, drugs and phones into the cells.

"Right now we need to join forces, not discuss who is to blame. Of course we need to know how the guns were taken inside, everything should be checked. But right now it's time to regain control," Sergio Fontes, Amazonas state justice minister, told Al Jazeera.

The government has promised to build more jails, but that is expected to take years. In the meantime, Brazil's security forces must contain a prison system at breaking point, not knowing when or where the next riot will occur.