Police said late Wednesday that they arrested a fourth suspect after a group of white supremacists allegedly opened fire on Black Lives Matter protesters Monday night in Minneapolis. Local prosecutors have until Monday to file charges against the men being held, according to The Minneapolis Star-Tribune.

The Minneapolis Police Department said in a news release that they had arrested Joseph Daniel Backman, 27, in connection with the shooting that left five protesters injured. Police also confirmed the Tuesday arrests of Allen Lawrence “Lance” Scarsella III, 23; Nathan Wayne Gustavsson, 21; and Daniel Thomas Macey, 26. Blackman, Scarsella and Gustavsson appear to be white while Macey appears to be Asian.

Police said in the news release that they weren’t seeking any more suspects although the investigation was ongoing with the help of the FBI.

Court records showed one of the men who was arrested called a police officer he knew to confess to shooting the demonstrators.

A search warrant application showed that Scarsella called a Mankato, Minnesota police officer identified only as “Levin,” who was an old high school friend of his, at 1 a.m. Tuesday to confess to the shooting, according to the Star-Tribune. Scarsella told the officer that he went to the protests, sparked by the fatal police shooting of 24-year-old Jamar Clark, to livestream and then got into a confrontation with demonstrators, according to the newspaper.

Police searched Scarsella’s Bloomington home for white supremacist paraphernalia and found camouflage clothing, ammunition and several firearms, including an AR-15 rifle, according to the warrant obtained by the Star-Tribune.

The four men arrested appeared to connect through 4chan message boards for firearms enthusiasts and racially charged political commentary, according to the newspaper. The Star-Tribune also reported that Gustavsson and Macey were both are students in the gunsmithing and firearms technology program at Pine Technical and Community College.

Hennepin County Attorney Mike Freeman told the Star-Tribune that an extenstion for prosecutors to file charges against the four men expires at noon Monday. Previously, the newspaper reported that authorities were weighing whether to treat the shooting as a hate crime.