Chad police officers control men on April 4, 2015 on the N'Gueli bridge, marking the border between Chad and Cameroon near N'Djamena
Yaounde (Cameroon) (AFP) - Empty streets, body searches and tips to police embody the fear that Boko Haram has instilled in northern Cameroon, where they killed more than 40 people in suicide bombings in July.
Raiders from the Nigerian sect later kidnapped 135 villagers and killed eight others in a pre-dawn strike across the border last Tuesday, police and local sources said.
Boko Haram has attacked villages in Cameroon's Extreme North region for about two years, but the horrific bombings mark a change of tactics, while Cameroonian troops have joined a regional force to tackle the Islamists.
The suicide bombers can be young women and even teenage girls, who behave like locals and blend in at crowded places to cause maximum casualties.
Residents of Maroua, the main town in the Extreme North, were spared until successive blasts tore though the bustling central market and a bar on July 22 and 25. Those bombs killed 33 people and wounded dozens more.
"We're very worried and no longer know where to turn," says Albert, a worried father.
"Should we send the children to school when the next school year starts?" he ponders. "Boko Haram is against Western education and may very well carry out attacks on schools."
The sect's name loosely translates as "Western education is forbidden", and Boko Haram notoriously abducted 276 Nigerian schoolgirls in April last year.
Some managed to escape but more than 200 are believed to be held in the large Sambisa forest, where the Nigerian army this week said it had freed 178 captives.
- 'People like you and me' -
Boko Haram has frequently massacred students in northeastern Nigeria during an insurgency with the aim of establishing an Islamic caliphate, at a cost of at least 15,000 lives since 2009.
"When you see somebody who isn't familiar in the neighbourhood, you call the police," says Oumarou, who works for a Maroua logistics firm.
He has sent his family away to Douala, Cameroon's economic capital on the Atlantic, more than 1,300 kilometres (810 miles) away.
Information Minister Issa Tchiroma Bakary has meanwhile heaped praise on an astute taxi-motorcycle driver who turned in a 15-year-old boy carrying explosives last week.
The driver found the teen was behaving suspiciously and decided to drive him to a police station, where he was detained. Two other suspects were picked up.
"Their objective was to blow up inside a mosque," Bakary said.
Security has been tightened repeatedly in Maroua. When the market closes at 5:00 pm, "everybody goes home. There is nobody left on the streets apart from the soldiers," Oumarou says.
Sources in the security forces believe that Boko Haram infiltrators and sympathisers have operated in Maroua for months, relaying information to their chiefs.
"They are people like you and me," a Cameroonian army officer says. "It's almost impossible to identify them."
Bus terminals catering for southern destinations, notably big cities like Douala and the capital Yaounde, are closely watched. Passengers are always frisked as they board their coaches.
"You feel the threat most because of all the checkpoints on the roads," says Olivier, a young French expatriate in Douala.
"The police have tightened up their searches. They make us empty our cars completely, and our bags."
- 'We no longer know who's who' -
In Yaounde, police and troops are omnipresent.
"People have been very ill at ease since there were suicide attacks" in the north, trader Abdoulaye Sani says.
"We no longer know who's who. I'm afraid when I'm walking... I'm afraid that something will happen, that a bomb will explode and take me with it," adds the young man.
In one working-class district with a large Muslim community, police last week used strong-arm tactics during searches of houses and mosques. They rounded up several dozen people, according to the local media.
The information minister said that security forces were carrying out a sweep in several parts of the country, which led to the arrest of "many suspects".
But such assurances fail to reassure.
"We don't go to parties, we avoid places where there is too much of a crowd," says Darly, an adolescent in the capital.
"We're afraid that the suicide bombers will come here to Yaounde," she said.