Former CNN anchor Don Lemon was taken into federal custody on Thursday night following a federal investigation linked to a protest at a church in Minnesota.

A grand jury was empanelled in connection with the case, and the Federal Bureau of Investigation (FBI) and Homeland Security Investigations were involved in the arrest. It is not yet clear what charges Lemon may face.

The arrest stems from an anti-ICE protest at Cities Church in St Paul, Minnesota, CBS News reported, citing multiple sources with direct knowledge of the matter. Demonstrators entered the church after discovering that an Immigration and Customs Enforcement official was among the church’s pastors.

Last week, a federal appeals court declined to order a lower court judge to sign arrest warrants for Lemon and four others connected to the protest. One judge said there was probable cause to justify the arrests, according to court filings cited by CBS News. Several people have already been charged in connection with the incident.