Immigration and Customs Enforcement have taken the family of a man suspected of attacking a pro-Israel demonstration in Boulder into custody, officials confirmed on Tuesday.

“Today, DHS and ICE are taking the family of suspected Boulder, Colorado terrorist, and illegal alien, Mohamed Soliman, into ICE custody," said DHS Secretary Kristi Noem. "This terrorist will be prosecuted to the fullest extent of the law. We are investigating to what extent his family knew about this heinous attack, if they had knowledge of it, or if they provided support to it. I am continuing to pray for the victims of this attack and their families. Justice will be served.”

Soliman and his wife and five children live in Colorado Springs, about 100 miles south of Boulder. Federal agents were first seen at the address there on Monday.

"He stated he left an iPhone at the house, hidden in a desk drawer, with messages to his family," a criminal complaint against him says. "He also stated that he left a journal inside his house."

When agents arrived at Soliman's house on Monday, his wife was observed leaving. She reportedly went to the local police station and turned over the iPhone.

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Police said Soliman used a makeshift flamethrower and threw two incendiary devices into a group of demonstrators who were rallying in support of hostages still held in Gaza in Boulder over the weekend. He has been charged with a federal hate crime and 16 counts of attempted murder.

The FBI is investigating the incident as a targeted act of terrorism.

Soliman is being held at the Boulder County Jail on a $10 million bond. He made a brief court appearance Monday but did not speak. His next hearing, where the charges will be reviewed, is scheduled for June 5. If convicted of the most serious charges, he could face life in prison.