Nigerians refer to them as bandits - a word that does not quite do justice to what are in fact networks of sophisticated criminals who operate across large swathes of northern-western and central Nigeria.
Gangs on motorbikes terrorise the region, stealing animals, kidnapping for ransom, killing anyone who dares confront them and taxing farmers - it's a huge money-making operation.
Over the last four years the security forces have not been able to get a handle on the situation, which millions of Nigerians feel is out of control.
Last week President Muhammadu Buhari inaugurated the Dutsinma-to-Tsaskiya road in his home state of Katsina but few people dare travel on it after countless attacks.
Most top government officials, including security chiefs, take the train linking the capital, Abuja, to Kaduna because of frequent abductions on the road between the two cities.
A serving army general was recently killed on the main road from Abuja to central Kogi state and his sister, who had been travelling with him, was kidnapped.
This week, 13 military police were killed in an ambush in Zamfara state when at the same time at least 150 villagers were abducted.
At the moment at least 300 students are being held by kidnappers who seized them from their schools in Kaduna, Niger and Kebbi states at different times over the last two months - many taken in broad daylight.
Some are Islamic primary school students as young as five and most of them, if the kidnappers are to be believed, have fallen sick.
In all these cases, the gangs are asking for huge amounts of money to release the children - ransoms the parents cannot afford, while the authorities insist that they will neither pay ransoms nor negotiate with criminals.
The kidnappers, whose hideouts are in vast camps in forests, are brazen.
As they hold out for payment, they hassle parents with demands for bags of rice, beans and cooking oil to feed their captives.
Dozens of schools spread across at least five northern states have been closed by the authorities as they are unable to protect them.
Food prices spiral
This has not stopped the gangs, who have recently turned to targeting more high-profile figures such as a local emir and his family.
Hundreds of villages have been deserted after some of the most brutal and deadly attacks.
In some areas, the gangs dictate what the locals can do and levy taxes.
Such insecurity in one of the country's rich agricultural belts is clear for all to see.
This year has already seen unprecedented rises in the prices of staple foods like maize, rice and beans that are grown there.
Now in the middle of the farming season huge tracts of farmland are inaccessible.
The one clear advantage - air power - that the authorities seemed to have over the criminals is now under threat.
Reports that a military jet had been shot down on Sunday by one of the gangs were at first flatly denied.
But when villagers in the area told reporters they had helped the pilot to escape to safety, the military issued a statement with a more positive spin - commending the "gallant pilot" who had come under "intense enemy fire" after a "successful" mission.
The authorities may have tried to downplay the incident but it shocked security analysts.
"We know the bandits have all those bazookas, rocket launchers… We didn't believe they have the technical know-how and capacity to use them," retired security official Mike Ejiofor told the Vanguard newspaper.
Some of the gang members have been boasting of their alliance with Islamist Boko Haram militants, who have waged a decade-long insurgency in north-eastern Nigeria and some of whom are now linked to the Islamic State group. Such allegations have not been independently verified.
However one bandit leader holding about 90 schoolchildren has told their parents that he will marry off the girls to his fighters and indoctrinate the boys to join his group - tactics used by Boko Haram to expand.
For one columnist, Boko Haram specialist Bulama Bukarti, these outrages take the issue to another level.
"It is time for Buhari to declare these beasts as the terrorists that they are and deploy all available resources to fight them. There can be no ifs, no buts, no equivocation."
Mr Ejiofor echoed this, saying: "The military should go all out for them and carry out sustained bombing of their enclaves."
The communities affected are at their wits' end over the growing boldness of the criminal gangs.
But with more calls for more military intervention, some may be looking nervously at the three states left devastated by Boko Haram - where millions are still living in overcrowded camps far from their old homes and livelihoods.
Related stories: 100 kidnapped villagers freed after 42-day captivity