BOULDER, Colo. — The wife and five children of the man accused of throwing Molotov cocktails at demonstrators in Boulder who were calling for the release of Israeli hostages in Gaza, injuring 12 of them, were taken into custody Tuesday by federal immigration authorities, officials said.

Mohamed Sabry Soliman, who was disguised as a gardener, had 18 Molotov cocktails and had planned to kill all the demonstrators but apparently had second thoughts, throwing just two during Sunday’s attack in which he yelled “Free Palestine,” police said. Soliman, 45, didn’t carry out his full plan “because he got scared and had never hurt anyone before,” police wrote in an affidavit.

The two incendiary devices he did throw at the group of about 20 people staging their weekly demonstration were enough to injure more than half of them, and authorities said he expressed no regrets about the attack.

Federal officials are investigating whether Soliman’s family knew about his plan, U.S. Secretary of Homeland Security Kristi Noem said.

— The Associated Press