One week after 26 students and staffers were gunned down in a Newtown, Conn. school, a 14-year-old Bucks County boy is in custody for allegedly threatening to "randomly kill students and staff" at Council Rock South High School, police said Friday.

A tip from the parent of another student led police to the Richboro home of the ninth grader, where they confiscated two 9mm, World War II-vintage handguns, a replica AK-47 rifle, plus knives, machetes and swords, Northampton Township Police Chief Barry Pilla said.

"I believe that because of the cooperation of the community and the school administration, we dodged a bullet," Pilla said at an 11 a.m. news conference. "This was a credible threat."

The threat prompted the district to close the school in the Holland section of the township, affecting 2,200 students, plus faculty and staff. It was specific to that campus, Superintendent Mark Klein said, so the district's other schools and 9,360 students were not affected.

Four other high schools in lower and central Bucks also were targeted with threats Thursday, but they were investigated and discounted, and classes continued as scheduled, officials said.

In the Council Rock case, the 9th grader was being held in the county Youth Detention Center in Edison, on charges of making terroristic threats and possession of a firearm by a minor.

Police did not know why the threats had been made, Pilla said.

The student's mother, Lizabeth Donohoe, 50, was being held at the county prison on charges of possession of a firearm and endangering the welfare of children.

Police were trying to determine who owned the handguns and where they came from, Pilla said.

The ninth grader made statements Thursday at the school "indicating that he was going to bring a gun and knives into the school building Friday morning and randomly kill students and staff," Pilla said.

Another student alerted his parent about the threats, and the parent called police, Pilla said.

"He's a hero," Klein said about that student.

The 9th grader did not post threats on the Internet, but other students wrote about them on Facebook, the police chief said.

At the 9th grader's house on Cypress Avenue, police found 9mm Browning and FB Radom handguns and the replica AK-47 rifle in his bedroom, Pilla said. There were empty clips for each handgun, but no ammunition, he said.

The replica rifle was so authentic that if the student "confronted law-enforcement officers with that weapon, they would shoot him," Pilla said.

Police also found knives, machetes and swords throughout the house, he said. Another search was planned later Friday, he said.

While police were arresting the student and his mother, the teen's father showed up and was arrested on charges of resisting arrest and obstruction of justice. Vincent Mario Russo Jr., 48, of the 500 block of West Street Road in Feasterville, was released and will receive a summons, Pilla said.

The mother also was charged with possession of marijuana and drug paraphernalia. She was being held on $100,000 bail.

Pilla and Klein declined to say whether the student had been in trouble before Thursday.

Police dogs were used to search the school, and no evidence was found, Pilla said.

The school was cleared Friday morning, but the district had notified all families at midnight that South would be closed as a precaution.

Authorities also received threats Thursday about Neshaminy, Pennsbury, Bensalem and Central Bucks South high schools, county Emergency Services Coordinator John Dougherty said Friday.

"Police assured us the threats were unfounded and it was safe to bring students in," said Susan Harder, administrative assistant to the Bensalem superintendent. "There is extra police on campus ... we continue to be on alert."

On Wednesday at the Spring-Ford Senior High School in Chester County, a student who was upset over a grade made threatening statements, authorities said.

The student was charged with terroristic threats, harassment and disorderly conduct, said Limerick Police chief William Albany.

The district has a zero tolerance policy. The district released a statement indicating disciplinary measures were also being taken.

Albany said while the student said he would "make last week look like nothing" referring to the Newtown shootings, police and school officials did not feel there was any imminent danger. The student did not have any weapons and there were none at home, he said.

"When criminal charges are filed, it gives the system a little more leverage," he said. The goal was to get the student help and the charges insure the individual complies. The student is now in a treatment program, he said.

"I think this young man puts a lot of pressure on himself."

A similar incident happened a few weeks ago at the district's vocational education school and was handled the same way, Albany said.

Staff Writer Mari Schaefer contgributed to this story.