Police in the U.S. arrested a man Thursday in connection with a mass shooting in South Carolina Wednesday. Twenty-one year old Dylann Storm Roof is suspected of killing nine people at an African-American church in the city of Charleston. Federal investigators say they will pursue hate crimes charges against the suspect.

Investigators say the suspect walked into the church during a weekly prayer meeting. He sat with the churchgoers for about an hour before he started shooting.

In a televised speech on Thursday, President Barack Obama said he and his wife, Michelle, personally know several members of the church, including the pastor who was murdered.