Family of Boulder suspect arrested by immigration officers

Immigration authorities have in custody the wife and five children of the man suspected of carrying out Sunday's incendiary attack on Jewish demonstrators in Boulder, Colorado, US Homeland Security Secretary Kristi Noem said.

Mohamed Sabry Soliman, 45, has been charged with attempted murder, assault and possession of an incendiary device after a dozen people were injured at a march calling for the release of Israeli hostages. He also faces a federal hate crime charge.

"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," Noem posted on X.

Officials say the suspect shouted "Free Palestine" as he threw two petrol bombs into the crowd.

One of Mr Soliman's daughters was recently awarded a scholarship by a local newspaper in Colorado Springs.

"Coming to the USA has fundamentally changed me," she wrote in the scholarship application.

"I learned to work under pressure and improve rapidly in a very short amount of time. Most importantly, I came to appreciate that family is the unchanging support."

The newspaper reported she was interested in studying medicine.

A profile in the Gazette newspaper noted she "was born in Egypt but lived in Kuwait for 14 years" and relocated to the US two years ago.

The newspaper also reported: "When she was young her father underwent a difficult surgery that restored his ability to walk."

After his arrest, Mr Soliman told police he planned the attack for after his daughter's high school graduation, according to the FBI.

The defendant appeared in court on Monday via a video feed from the Boulder County Jail for less than five minutes, standing and wearing an orange jumpsuit.

He answered "yes" to some procedural questions from the judge, but otherwise did not speak.

He is next due in court for the formal filing of charges and a bail hearing on Thursday.