Fearing federal agents asking to search a Chicago elementary school Friday morning were from Immigration and Customs Enforcement, school officials denied them entry. But the U.S. Secret Service later said its agents were there pursuing an investigation.

A rumored sighting of immigration agents attempting to enter an elementary school on Chicago’s Southwest Side on Friday was in fact U.S. Secret Service agents investigating a threat, a federal spokesperson said late Friday afternoon.

Mayor Ras Baraka said he was "appalled" and "angry" and blasted ICE for also detaining U.S. citizens, including a veteran. ICE said citizens may be questioned during an investigation.