A Pennsylvania man remained jailed on Sunday after being accused by authorities of planning a mass school shooting for later this month that would have coincided with the anniversary of the Columbine High School massacre.Police allege Braeden Phillips, 20, had planned to commit a mass shooting at State College High School in Central Pennsylvania on April 21, one day after the 26th anniversary of the deadly Columbine High School shooting, according to a criminal complaint.Police allege Phillips had compiled a hit list and that the shooting would have taken place at around 8:40 a.m. a high traffic time for students and staff near the schools main staircase. Officials cited in the complaint allege that Phillips planned to place bombs in the school bathrooms.Two teenage boys went on a killing rampage at Columbine High School in suburban Denver on April 20, 1999. They shot and killed 12 classmates and a teacher, and wounded two dozen others before taking their own lives.Phillips has been charged with conspiracy to commit murder and unlawful possession of a firearm. He was being held without bond at the Centre County Correctional Facility because he was deemed an extreme danger to the community, according to court records.RELATED STORY | Resilient, compassionate, tenacious: Columbine survivor Anne Marie Hochhalter remembered by family, friendsCourt records did not list an attorney who could speak on his behalf.Police were trying to determine if anyone else was involved in the plan. Authorities allege Phillips said a juvenile friend of his also was going to take part in the shooting.State College Police would like to recognize that the success of this investigation would not have been possible without the initial report made by a concerned citizen. This illustrates the importance of see something, say something, police said in a statement.Authorities were first alerted to the plot by staff members at a Centre County youth center, who told police a resident had shared information about it. Police interviewed Phillips' friends and others, who told investigators that Phillips detailed how he planned to carry out the shooting and showed them a handgun.When police asked if Phillips had any issues or past grievances with State College High School, a friend said Phillips had told him, the school did not serve his educational needs and failed him, according to the complaint.Police allege Phillips initially planned to carry out the shooting on April 20, which would have been the 26th anniversary of the Columbine shooting, but that he changed the date because April 20 falls on a Sunday this year.Phillips was set to have a preliminary court hearing on Wednesday. ...read more read less