(Reuters) - A group of protesters shouting anti-immigration slogans blocked the arrival of two buses carrying undocumented Central American families to a U.S. Border Patrol station in California on Tuesday after they were flown to San Diego from Texas.

The migrants, a group of adults and their children numbering about 140 people, were en route to the facility in Murrieta, California, where U.S. immigration officials said they most likely would be released under limited supervision to await deportation proceedings.

The arrival of the undocumented immigrants at a border patrol station in Murrieta, about 60 miles (97 km) north of San Diego, sparked an outcry from the town's mayor, Alan Long, who said the migrants posed a public safety threat to his community.

The immigrant children and their parents arrived by plane at midday in San Diego from Texas, where they were recently apprehended while trying to illegally cross the U.S.-Mexico border, and were put on two unmarked buses for the ride to Murrieta.

A group of 150 protesters filled a street leading to the access road for the processing center in Murrieta, blocking the two buses from reaching the facility, and disregarding orders shouted by local police to disperse.

Police did not attempt to intervene physically to break up the demonstration.

After about 25 minutes, the two buses backed up, turned around and left. A board member of the union representing border patrol agents, Chris Harris, said the buses would likely be rerouted to one of six other Border Patrol stations in the San Diego sector.

A separate group of about the same number of immigrants were being sent on Tuesday to a similar processing facility in El Centro, California, a desert community about 100 miles (160 km) east of San Diego, U.S. immigration officials said.

Both groups are part of a growing wave of families and unaccompanied minors fleeing strife-torn Central American countries of Guatemala, El Salvador and Honduras that have been streaming by the thousands since last year into Texas through Mexico.

The surge of undocumented children and families from Central America has left U.S. immigration officials scrambling to handle large numbers of migrants that, by law, the government is barred from deporting immediately, as they normally could with illegal border crossers whose country of origin is Mexico.