Kris Brown, president of Brady United Against Gun Violence, said red flag laws, which allow courts to issue "extreme risk protection orders" (ERPO) removing firearms from individuals considered at risk of harming themselves or others, could help prevent such shootings.
"This is the kind of protection that if people in Maine had known about it and the courts were primed with the right kind of law to be able to enact these sorts of orders, could have potentially made a real difference here," she said.
Police circulated photographs of a bearded man in a brown hooded sweatshirt and jeans at one of the crime scenes armed with what appeared to be a semi-automatic rifle.
Public school districts in the area canceled classes on Thursday, and police urged residents to stay indoors.
