Federal authorities say six people have been arrested in Minnesota and California in connection with a terrorism investigation.

A spokesman for the Minnesota U.S. Attorney's Office says the arrests were made Sunday in Minneapolis and San Diego but there is no threat to public safety.

Spokesman Ben Petok did not give details about the charges but said they are related to an investigation in Minnesota in which authorities have been tracking youths who have traveled or tried to travel to Syria to fight with militants, including the Islamic State group.

An FBI spokesman said six people were arrested.

The U.S. Attorney's Office and the FBI planned a news conference Monday to announce details. The announcement will include details of a "joint terrorism task force operation."