(ABC News) -- Schools in Newtown, Conn., were placed on "lockdown" Monday after a phoned-in threat, a scare that one mom called a "horrible, evil thing to do" to a town still recovering from the December massacre of 20 first graders.
The schools were placed on modified lockdown, in which students were dismissed to parents or by bus, after a threat was called in to Hawley Elementary School, according to schools superintendent John Reed.
Reed said the threat was being investigated by police and the FBI and that it was not a "bomb threat," though he would not give details on the nature of the phone call.
Newtown police said they put schools on lockdown for "precautionary measures" but would not offer any other details.
Parents of Newtown students told ABC News they received an alert about the modified lockdown and police response. They were told to expect afternoon busses to be delayed, but otherwise not to worry.
The scare comes almost exactly six months after gunman Adam Lanza broke into Sandy Hook Elementary School on Dec. 14, 2012, and gunned down 26 people. He also killed his mother and himself during the rampage.
Karen Dryer, the mother of a kindergarten student at Sandy Hook school and a high school student at Newtown High School, said that she was badly shaken by the incident.
"Luckily it was short lived, but it was another nightmare of course," Dryer said. "It's still very raw, and for this to happen is just awful."
Dryer said she was expecting her daughter's school bus to drop her off from high school around 2:30 p.m. today when instead her daughter texted her, saying the schools were on lock down. Dryer immediately drove to Sandy Hook, where her son is in kindergarten, and received a phone call from the superintendent as she drove.
"He said they were on modified lockdown because there was very credible threats made to the Hawley school, toward the staff and students, and that it had been lifted but the police and FBI were following up," she said.
The staff at Sandy Hook let Dryer sign her sign her son out of class and take him home early. The school did not broadcast to the students that they were on lockdown, she said.
"My son already has anxiety issues, and we've had to work very hard with the school after the shooting in December to get him comfortable again because he was just terrified," she said.
As she and her son left the school, dozens of other parents pulled into the parking lot to pick up their children, she said.
"It's a horrible, evil thing to do to this community. It's pure evil to put the staff and children through this, it's just awful. I'm very very shaken up, and quite stunned. I think entire community is. It's just too raw," she said.