Maiduguri: Nigeria's city of fear
No-one in the Nigerian city of Maiduguri knows who to be afraid of most, a group of Islamist militants known as Boko Haram or the police.
The sect, thought to have been eliminated after a brutal uprising in 2009 in which hundreds of people were killed, is back and its members want revenge.
For the past five months they have been fighting a guerrilla war, killing policemen and people they believe helped the security services in the fight against them.
Residents of the city in the far north-east of Nigeria are trapped in the middle and anyone speaking about the sect does so nervously.
But they say it is the fear of the police which has made it so easy for the group to grow again.
The bustling markets and children playing in the streets belie the anxiety in the city which witnessed bloody battles in July 2009.
At night, although the military and police man checkpoints, life seems almost normal.
However, few people on the streets of Maiduguri would give their names when interviewed about the latest drive-by shootings.
"You never know who they are, they could be among you" said one man, who works near the railway station where 20 months ago the police laid out bodies of dead sect members.
Officials sealed their lips at the sight of a microphone, afraid to speak out and end up on a list for assassination by Boko Haram.
Traditional leaders who have given information about suspected militants to police have also been executed by gunmen.
The group's trademark attack is to ride up to their target on a motorbike - Maiduguri is full of motorbike taxis - and the pillion passenger opens fire with an automatic weapon, before speeding off.
Afterwards, police are reported to round up innocent people in areas where these hit-and-run executions occur, long after the attackers have sped away.
At the Special Armed Robbery Squad station in Maiduguri - known as "the Crack"- police are holding the wife of a suspected militant who escaped police arrest.
Although they do not accuse her of involvement in the attacks - they are preparing charges of "associating with criminals".
Yakaka, 20, and her two children, both under four, are being held almost as hostages.
"I have told the police the location of my family, but I don't think they have been told I am here. This is the situation I am in. See me here, my children are scared," she said.
Many people in Maiduguri fear that if they bring information to the police they will suffer the same fate, or worse.
Local residents dubbed the sect Boko Haram, which literally means "Western education is forbidden" in the Hausa language, before the uprising.
Sect members had set up a community living by strict Sharia principles around its mosque in Maiduguri. Amid the 2009 trouble, the name was then popularised by the Nigerian media.
However, the group calls itself Jama'atu Ahlis Sunna Lidda'awati Wal-Jihad, which in Arabic means "People Committed to the Propagation of the Prophet's Teachings and Jihad".
Their charismatic leader Mohammed Yusuf preached that Muslims should withdraw from corrupt, Western society, which included secular education and democracy, and base their lives on the teachings of the Prophet Muhammad.
Yusuf was killed by police after the sect was crushed. Police said he had tried to escape, but many believe he was executed - and the sect is now taking revenge.
The trouble in July 2009 began when officials fearing Yusuf's increasingly radical sermons calling for a jihad against the government sent the security forces to attack the sect's mosque.
Sect members returned fire and for four days had the run of the town in a killing spree.
When their ammunition ran out, the police moved in, killed more people and arrested many others - among them Nigerian journalist Ahmad Salkida.
He had followed the sect's growth since 2002 and was in personal contact with Yusuf before the violence began, so he was accused of being a sect member.
He believes he was about to be executed when his life was saved by a senior policeman he knew.
"The police officers guarding me were discussing which one was going to be the one who pulled the trigger," he told the BBC.
During his time in detention he saw as many as 50 young men being taken out of the cell they shared, never to return.
"That extra-judicial killing by the police really created a barrier between security agents and the general population," he said.
"For the average person, you don't like the sect, you don't like their activities, but you are afraid of the police and you don't trust them. It leads to confusion."
Abubakar Mohammed, newly arrived in Maiduguri and now the city's police chief, admits mistrust of his force has made the police's job difficult.
"The natives have refused to come forward and co-operate with us, so we are left with no option but to go all out and investigate our targets."
This involves arresting people for questioning.
"If you are innocent, we will release you," he says.
The police commissioner estimates the underground sect members now number about 400.
Last month a random car stop gave the police what he called a "breakthrough" in their investigations.
A cache of weapons was found that included over 800 rocket-propelled grenade shells.
A senior sect member contacted by the BBC by phone said the police's seizure was just part of their "armoury".
Using a nom-de-guerre of a warrior companion of the Prophet Muhammad, Abu Dujana said the sect would slay anyone they considered to be an enemy.
Questioned about the sect's ideology, he said members draw their ideas from the same pool of radical thought as al-Qaeda and Somali group al-Shabab.
"We do not want to hurt civilians, but we do not rule out using suicide bombs in the future."
His anger about the police was palpable.
"Once you help the police, you are as good as being a policeman, so we will slaughter you," he said.
In a warning Maiduguri's residents have taken to heart, Abu Dujana says the sect's fight against the government has only just begun.