Southern California couple charged amid "unprecedented" and "horrific" surrogacy probe, Los Angeles County DA says

The Los Angeles County District Attorney's Office on Tuesday announced charges in a child abuse case involving a couple who had 21 children removed from their home last year.

Guojun Xuan and Silvia Zhang of Arcadia, who were arrested at their home Tuesday morning, were set to be charged with several felonies, including conspiracy to commit child abuse and dissuading a witness, DA Nathan Hochman said. 

He is asking for bail to be set at $100 million.

 have been investigated by both local and federal officials for years as they've parented at least 25 children through surrogacy. Now, an apparent breakthrough in the case will take shape as DA Nathan Hochman and LA County Sheriff Robert Luna speak.

Earlier this year, CBS News spoke to 17 of the couple's surrogates from around the country, and all of them said they didn't know they were building such a large family. Many of the surrogates have claimed they were misled during the process and weren't aware of the other women carrying babies for the same couple.

Aerial images over the couple's home on Tuesday morning showed a heavy law enforcement presence, including apparent FBI agents on the property.

As of Tuesday morning, the exact charges were not immediately made clear.