Police investigating reports of hoax threats made at schools nationwide and in Mass., officials say

Several hoax threats against high schools were reported across the country on Monday, including in Boston and three other Massachusetts communities, and the FBI is assisting local police departments in investigating, authorities said.

Boston police were investigating threats aimed at Charlestown and East Boston high school that appeared to be a hoax. Both schools were placed in safe mode as a precaution, officials said.

“This is an ongoing investigation,” said Sergeant Detective John Boyle, a Boston police department spokesman. “We are aware that several threats were made nationwide at schools ... as of now our threats in Boston appear to be hoaxes.”

Boston Public Schools Superintendent Mary Skipper thanked the first responders who addressed the hoax calls at Charlestown and East Boston High Schools.

“Our team takes any threats against students and staff very seriously, and these incidents create unnecessary anxiety and stress for our students, staff, and families,” Skipper said. “This also takes school and city resources away from our communities. We condemn this hoax that happened here and in communities across Massachusetts in the strongest possible terms.”

Amesbury High School was also placed under lockdown Monday after police received a threatening call around 11:42 a.m., according to local police. The caller said he had a gun near the school and the recipient heard what sounded to be gunshots before the caller hung up.

Police checked and found no evidence of shots fired, police said. They turned the school day back to administrators after hearing from other law enforcement agencies about similar reports and determining the school was not in danger, police said.

“A preliminary investigation indicates that the police response to Amesbury High School this afternoon was driven by an apparent act of ‘swatting’ and other school districts in the region have reported similar incidents today,” police wrote.

David Procopio, a spokesman for the State Police, said a fake threat was also reported in Westfield.

“Several threats being made nationwide, all of which have been determined to be hoaxes, including Westfield,” Procopio said by e-mail.

Shortly after noon, police in Chelmsford said they received a 911 call from someone indicating they planned to “cause harm and inflict damage” at Chelmsford High School. Officers “extensively searched school grounds and secured the building” and determined the call was a hoax, police said.

“While there is no indication of any ongoing threat to the school community, police will remain at the high school through dismissal,” police said.

The FBI’s Boston office said it is working with police to identify the source of the hoax threats.

Law enforcement will use all available resources to investigate school threats until they can determine whether the threats are real or not, the FBI said in a statement. But this drains resources, the statement said, and can divert police from responding to an actual crisis.

“Hoax threats can shut down schools, cause undue stress and fear to the public, and cost taxpayers a lot of money,” the statement said.

However, the statement said, the public is urged to remain vigilant and report any suspicious activity to law enforcement immediately.

At Charlestown High School, students said they had to sit in silence for about an hour after lunch. Teachers turned off the lights, shut the blinds, and locked the doors.

A 17-year-old student named Leslie said she was in math class when the school went into safe mode.

“I was, like, really shaky because that’s really scary. We didn’t know if it was real,” she said. Other school shootings from the past year were running through her mind as she waited in the dark classroom, she said.

“I’m honestly still feeling really shaken,” Leslie said. “I sent my parents texts and everything.”

Another 17-year-old student, who identified herself as Carolina, said that she struggled to understand what was going on because she doesn’t speak English very well.

“They shut us in a room in a library,” Carolina said in Spanish. “We were scared, because we didn’t know what was happening. I’m still scared right now.”

Travis Andersen of the Globe staff and Globe correspondents Kate Armanini and Claire Law contributed to this report.