MCALLEN, Texas -- Protests and rallies around the country Saturday focused on the separation of families at the U.S.-Mexico border, and a number of congressional Democrats visited facilities holding children in Texas and California.

More than 2,300 children were taken from their families in recent weeks under a Trump administration "zero tolerance" policy in which people entering the U.S. illegally face being prosecuted. Parents and children were being detained separately. But after public outcry, President Trump on Wednesday ordered that they be brought back together.

Confusion has ensued, with parents left searching for their children. A senior administration official told CBS News that as of Friday night, about 500 children in custody of U.S. Customs and Border Protection were reunited with their parents. That leaves hundreds more who are still being held in facilities managed by the Department of Health and Human Services, which has formed a task force aimed at reuniting those children with their parents.

In Los Angeles, protesters flocked to the federal building to donate toys to the children who were separated from their parents at the border, CBS News' Carter Evans reports. On Friday night, protesters rallied outside the federal jail downtown, where detainees have been housed. About 100 separated children are believed to be somewhere in the city.

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A woman at the protest, Maria Vasquez, said she knows what the children are going through. She left her family in Guatemala to come to the U.S., spending months in detention before being granted asylum. She said it was all worth it.

"I'm not one of the persons Trump thinks I am," she said.

There were protests in downtown San Diego, and Sen. Kamala Harris visited a detention center along the border where immigrants are being held.

During one Texas protest Saturday, scores of protesters taking part in a rally attempted to block a bus with detained children on board that left a processing center. Many protestors sat on the pavement. Chants, like "let the children go" broke out.

Eventually, protest organizers asked the participants to move away, and the bus left.

There are signs of progress, CBS News' Weijia Jiang reported from the White House Saturday morning. But for all the children who remain separated from their families, there is no clear timeline for their reunion.

Events planned this weekend included a rally Saturday in Fort Worth, where the Texas Democratic Convention is being held, and a protest in Homestead, Florida.

The Democratic lawmakers visited detention facilities in McAllen and Los Fresnos. About a dozen people demonstrated ahead of the delegation's arrival in McAllen wearing white T-shirts that said, "I want my mommy."

Rep. Jackie Speier of California, along with others, spoke out about the conditions of the facilities. She said she saw children in "cages" with Mylar blankets.

Congressional Delegation reporting to the press what we saw in the facilities. Haunting scenes of asylum seekers including small children held in cages, covered in Mylar blankets. pic.twitter.com/2dZKWwXI4W — Jackie Speier (@RepSpeier) June 23, 2018

Sen. Bill Nelson, D-Fla., claimed on Twitter that he tried to enter a Florida facility — and was not allowed to enter. Lawmakers are generally required to give two weeks' notice ahead of a facility visit.

Just visited the Homestead, Fla. facility where 70 kids who were separated from their families are being held. They would not let me see the kids. They told me they have no plan in place to reunify them with their parents. pic.twitter.com/mpwOP7eNKv — Senator Bill Nelson (@SenBillNelson) June 23, 2018

Tens of thousands of immigrants traveling with their families have been caught on the southwest border in recent years, many fleeing gang violence in Central America. About 9,000 such family units have been caught in each of the last three months, according to U.S. border authorities.

The Trump administration announced plans in April to prosecute all immigrants caught along the southwest border with illegally entering the country. Parents were jailed and children taken to government-contracted shelters.

Now, the administration says it will continue with prosecutions and seek to detain families together during their immigration proceedings.

Immigration officials have said they could seek up to 15,000 beds in family detention facilities, and the Pentagon is drawing up plans to house as many as 20,000 unaccompanied immigrant children on military bases.

A sign welcomes people to the United States in the Texan city of Brownsville which has become dependent on the daily crossing into and out of Mexico on June 23, 2018 in Brownsville, Texas. Spencer Platt/Getty Images

Those proposals have also sparked an outcry from women's and children's advocates who say children don't belong in jail. They want minors to remain protected by a decades-old settlement governing the detention of immigrant children caught on the border. Under the agreement, children must be placed in age-appropriate facilities and released as quickly as possible.

The Trump administration is seeking changes to the settlement in federal court to try to deter more families from making the trip.