As of Wednesday, about 2,800 service members were deployed to the Los Angeles region, including 2,100 National Guard troops and 700 Marines, who have just completed training, according to a status update from U.S. Northern Command.

The Marines are expected to be serving alongside National Guard troops within the next 48 hours, the command said.

The Marines received training in de-escalation and crowd control among other things, according to the status update.

Both Marines and National Guard troops are serving as part of Task Force 51 under what's known as Title 10 status -- to protect federal personnel and federal property.

"They can and have accompanied ICE on missions, but they are not a part of the operations," according to the status update, referring to Immigration and Customs Enforcement. "Title 10 forces do not do law enforcement functions. They protect; they don’t participate."

The troops may "detain an individual in specific circumstances such as to stop an assault, to prevent harm to others, or to prevent interference with federal personnel performing their duties." However, the troops are required to then transfer custody to the appropriate civilian law enforcement personnel.

-ABC News' Luis Martinez

Demonstrations protesting the Trump administration's immigration enforcement operations took place in cities across the U.S. on Wednesday, including San Antonio, Texas.

Demonstrations in Texas' second-largest city remained peaceful. Large crowds gathered downtown and marched near City Hall, away from the historic Alamo, where Texas State Troopers and Texas National Guardsmen were staged.

A small group of demonstrators was seen near the Spanish Mission but eventually joined the bigger crowd at City Hall.

San Antonio police closed streets during the march.

-ABC News' Mireya Villareal and James Scholz

For the second night, a curfew is in effect for part of downtown Los Angeles that has been the site of protests and marches that have seen some clashes with authorities.

The curfew lasts until 6 a.m. local time.

LA Mayor Karen Bass said the nightly curfew, which first went into Tuesday, would likely remain in effect for multiple nights.

About a half hour before the curfew went into effect on Wednesday, the Los Angeles Police Department said a large demonstration at Grand Park in front of LA City Hall had splintered and was blocking streets in the Civic Center area.

Earlier, police said some protesters in a demonstration marching on Hill Street in downtown LA were throwing fireworks and rocks at officers.

Several people protesting ICE detentions were arrested in downtown Manhattan on Wednesday. Officers began detaining people after the protest, which started in Foley Square near City Hall, began moving down Broadway before being stopped by police at the intersection of Broadway and Duane.

The arrests appeared to take place after protesters did not clear a crosswalk when ordered to by police.

Hundreds of protesters remain in the area, chanting behind barriers, with dozens of officers standing by.

-ABC News' Will McDuffie