A few hundred metres from an iconic mosque in west Mosul, Iraqi sniper Salah al-Zuheiri has his eye glued to his scope as he searches for Islamic State group jihadists.
Iraqi forces are battling to retake Mosul from IS, after the group overran the city in 2014 and its leader proclaimed a "caliphate" from the mosque in its Old City.
IS "fighters are within range. We're tracking them day and night," says Zuheiri, a sniper with the Iraqi federal police who has taken up position some 300 metres (yards) from the Al-Nuri Mosque.
Inside a darkened room in a four-storey building retaken from the jihadists, Zuheiri tries to steady his rifle on sandbags.
A map of the surrounding neighbourhood, hand-drawn in red, hangs on the wall in front of him.
Zuheiri and his colleagues stay in the same positions for up to 12 hours a day, he says, for two weeks straight.
They "get food three times a day", he adds, and leave their positions "only when it's really necessary, like to go to the bathroom".
"We kill between three and five jihadists a day," he says.
Nearby, Murtada al-Lami lies on his stomach, the end of his barrel jutting out through a tiny hole in the wall in the direction of the Al-Nuri Mosque and the adjacent "Hadba", a leaning minaret that has long been Mosul's most recognisable landmark.
IS leader Abu Bakr al-Baghdadi made his only public appearance at the mosque in July 2014 to declare a self-styled "caliphate" in parts of Iraq and neighbouring Syria.
- 'Human shields' -
To help the snipers find their targets, in a nearby room Iraqi soldiers take turns tracking IS fighters through binoculars.
And on a screen, members of a special unit survey thermal footage sent in from aircraft above the city.
"We're the ones who decide to shoot or not. We also have thermal binoculars, but we check the data with our colleagues to avoid an error," says Lami.
An officer in the group, who asks to remain anonymous, says snipers recently killed an IS emir, or leader, in west Mosul.
"Our snipers killed an IS emir on the west bank, creating great confusion in the Old City," he says, referring to the west bank of the River Tigris, which divides the city.
Fearing air strikes, jihadists went to the leader's funeral unarmed, the officer says, "but forced civilians to attend to act as human shields".
The presence of civilians in the Old City is a major obstacle for Iraqi forces fighting to retake west Mosul after seizing the east in January.
The United Nations says some 600,000 civilians remain in IS-held sectors, which include two thirds of the Old City, a warren of narrow streets.
As military vehicles cannot advance in the historic city centre, last month, General Raed Shakir Jawdat said dozens of snipers had been deployed on its roofs to cover advancing troops.
But IS also has snipers of its own.
"A few days ago a jihadist fired at me, but he hit the wall behind me," says Zuheiri. "I located his position and shot him down quickly."