Agents from Immigration and Customs Enforcement executed search warrants at several sites, including a clothing warehouse. Here, tensions rose as a crowd attempted to prevent the agents from leaving the scene.

Sirens blared as protesters surrounded black SUVs and tactical vehicles.

Officers threw flash bangs into the street to disperse people as they shouted and filmed the scene with their cell phones.

One demonstrator tried to physically stop a vehicle from leaving.

According to Yasmeen Pitts O’Keefe from Homeland Security Investigations, a total of 44 individuals were apprehended due to immigration violations across various locations.

The president of SEIU California, a major labor union, was arrested and charged for impeding a federal agent while protesting, the US Attorney’s office said.

Los Angeles Mayor Karen Bass said the activity was meant to “sow terror” in the nation’s second-largest city.

Federal immigration authorities have been ramping up arrests across the country to fulfill President Donald Trump’s promise of mass deportations.

Todd Lyons, the head of US Immigration and Customs Enforcement, defended his tactics earlier this week against criticism that authorities are being too heavy-handed.

He has said ICE is averaging about 1600 arrests per day and that the agency has arrested “dangerous criminals.”

Protests recently broke out after an immigration action at a restaurant in San Diego and in Minneapolis, when federal officials in tactical gear showed up in a Latino neighborhood for an operation they said was about a criminal case, not immigration.

Protesters chant ‘set them free’

In Los Angeles, federal agents executed search warrants at three locations, O’Keefe said.

But Angelica Salas, executive director for the Coalition of Humane Immigrant Rights, or CHIRLA, said advocates were aware of activity at seven locations, including several Home Depot parking lots and a doughnut shop.

At the warehouse in the fashion district, agents had a search warrant after they and a judge found there was probable cause the employer was using fictitious documents for some of its workers, US Attorney’s Office spokesperson Ciaran McEvoy confirmed.

Dozens of protesters gathered Friday evening outside a federal detention centre in Los Angeles where lawyers said those arrested had been taken, chanting “set them free, let them stay!”

Other protesters held signs that said “ICE out of LA!” while others led chants and shouted from megaphones.

Some scrawled graffiti on the building facade.

Officers holding protective shields stood shoulder to shoulder to block an entrance. Some tossed tear gas canisters to disperse the crowd.

Officers wearing helmets and holding batons then forced the protesters away from the building by forming a line and walking slowly down the street.

“Our community is under attack and is being terrorised.

These are workers, these are fathers, these are mothers, and this has to stop. Immigration enforcement that is terrorising our families throughout this country and picking up our people that we love must stop now,” Salas, of CHIRLA, said at an earlier press conference while surrounded by a crowd holding signs protesting Immigration and Customs Enforcement.

One detainee sent to Mexico

Yliana Johansen-Mendez, chief program officer for the Immigrant Defenders Law Centre, said her organisation was aware of one man who was already deported back to Mexico after being picked up at a Home Depot on Friday morning.

The man’s family contacted her organisation and one of their attorneys was waiting for hours to speak to him inside the detention center, she said.

Authorities later said he had already been removed, and the man later contacted his family to say he was back in Mexico.

Videos from bystanders and television news crews captured people being walked across a Home Depot parking lot by federal agents as well as clashes that broke out at other detention sites.

Outside the warehouse, KTLA showed aerial footage of agents leading detainees out of a building and toward two large white vans waiting in a parking lot.

The hands of the detained people were tied behind their backs.

The agents patted them down before loading them into the vans.

The agents wore vests with the agency acronyms FBI, ICE and HSI.

Armed agents used yellow police tape to keep crowds on the street and sidewalk away from the operations.

Immigrant-rights advocates used megaphones to speak to the workers, reminding them of their constitutional rights and instructing them not to sign anything or say anything to federal agents, the Los Angeles Times reported.

Katia Garcia, 18, left school when she learned her father, 37-year-old Marco Garcia, may have been targeted.

Katia Garcia, a US citizen, said her father is undocumented and has been in the US for 20 years.

“We never thought this would happen to us,” she told the Los Angeles Times.