New Orleans residents in fear as immigration crackdown descends on their cityZoë HigginsA CBP guard holding a sniper rifle points it at a roof during a recent arrest in New OrleansTwo labourers stand on the roof of a house in Kenner, outside New Orleans, as US Border Patrol agents clamber up a ladder, getting closer. As the agents move in, trying to arrest them, the men step to the roof's edge, poised in an apparent act of resistance - but it's too high to jump. On the ground in the mostly Latino neighbourhood, an officer trains his weapon towards the rooftop while a sniper moves into position. Now, neighbours, activists, and crews of local press are gathering at the scene, watching in bewilderment: US President Trump's new front line on immigration enforcement has just arrived. It is day one of "Catahoula Crunch", as the Department of Homeland Security (DHS) has labelled its operation, taking its name from an American leopard dog known for being well-muscled, powerful and territorial. "These people came to work today to provide for their families and themselves," said Zoe Higgins, an activist documenting the Border Patrol operation in New Orleans."That they could just be abducted, removed from all stability - I can't imagine how terrifying that is," she said, shortly after the agents coaxed the men down and detained them. According to DHS, its agents were conducting immigration enforcement this week when "several illegal aliens climbed on the roof of a residential home and refused to comply with agent commands". An "illegal alien" was arrested, DHS officials told the BBC, but they did not answer questions about the immigration status of the labourers involved, nor whether agents had a warrant to access the property. CBSBorder Patrol commander Greg Bovino walks through downtown New Orleans with agentsOn Thursday, DHS reported in a news release that dozens of people who had either been arrested or convicted of various crimes were arrested in the Louisiana operation. It is the fourth major city targeted in Trump's immigration clampdown, after he promised the biggest mass deportation operation of undocumented migrants in history.