In what is becoming a familiar scene, Gray-New Gloucester High School was evacuated last Friday following a bomb threat.

The evacuation came three days after a similar incident at the middle and elementary schools in Cape Elizabeth, which in turn came less than three weeks after a bomb threat closed Augusta schools.

It’s not only happening in Maine. Throughout the United States, schools are receiving threats of violence at a rate unheard of just two years ago, a result of the ease, distance and anonymity the Internet provides.

Though the vast majority are hoaxes, threats of all kinds force school administrators and public safety officials to weigh safety against the disruption caused when the school day is interrupted. But as the threats increase in regularity — Augusta schools have been shut down four times in less than year — those determinations become even more difficult.

Unfortunately, the threats may be a fact of life in a culture where people use technology to lash out at others over a simple grudge, or just to get a response. That makes it imperative that schools be prepared to accurately assess threats so that disruption is kept to a minimum.

Otherwise, schools may find themselves disrupted often.

While police dogs were searching Augusta schools on March 4, officers were doing the same at dozens of schools in Northern Virginia and New Jersey, all as a result of threats apparently from the same source.

It was similar to an incident in January, when dozens of schools in at least seven states were targeted.

Like many others that day, Gardiner Area High School received a computer-voiced “robo-call,” similar to those sent to voters during election season, except instead of touting a candidate, they say a bombing or shooting is imminent.

The superintendent of schools in the Taunton, Massachusetts, area kept schools open after receiving one of the January threats, saying it was “non-specific.”

But she was in the minority. Most administrators erred on the side of caution and closed schools.

When that happens, students lose a day of classes, parents are forced to arrange rides and supervision, there’s often a costly police response, and everybody is subjected to what can be an anxiety-ridden process.

That’s not much of a problem when it happens infrequently, but that is not always the case anymore.

Services that send robo-calls can be found easily on the Internet, and tech-savvy individuals can send tough-to-trace messages in any number of ways. And while some threats have a connection to their target, many others are from people who just like to provoke a reaction from afar.

A study of the first half of the 2015-16 school year found 745 bomb threats, a 143 percent increase over the same time frame the year before. Another found a 158 percent increase from 2013-14 to 2014-15. Security experts do not see the trend slowing down.

Harsher penalties are necessary to make perpetrators think twice, but technology may keep them a step ahead of police.

So schools must work with police to prepare for threats, and to create assessment teams to determine if a closing is necessary.

They also should be able to adjust security to appropriate levels so that threats can be investigated without disrupting school, and so that they can communicate easily and effectively with parents, students and staff if they must cancel classes.

It’s a shame that threats are on the rise, but now schools at least know they have to be ready.