Three Maine towns — Lewiston, Lisbon and Bowdoin — have been ordered to shelter in place while a manhunt continues for the suspect in shootings that killed at least 18 people. The suspect is considered armed and dangerous, according to Maine officials.

Andrea Cabral, former Massachusetts secretary of public safety who was involved in the decision for towns to shelter in place following the search for the Boston Marathon bombing suspects in 2013, told Boston Public Radio on Thursday that such measures are an extreme response.

"It’s not a decision that any elected official, especially a governor, takes lightly. ... You balance it against the relative, for lack of a better word, 'inconvenience,' of people having to stay at home and schools having to be closed, and businesses having to be closed, against the potential harms," Cabral said.

Cabral said there are a few reasons why officials choose such an extreme measure.

“You want to minimize the amount of movement in a particular community. ... You’re plowing the road, essentially, for law enforcement to have a clear view of tracking down who they’re looking for,” she said.

A shelter in place advisory also protects people from potential danger by keeping them out of public places.

But Cabral said, ultimately, what matters most is addressing the causes of gun violence.

“Literally, people in several towns in Maine are being held hostage to finding this one person, with assault weapons, who has not only killed a bunch of people in Maine, his continued presence ... is ensuring that people will have to shelter in place and remain hostages in their own community until he is found,“ Cabral said. “How is that remotely acceptable?”