HARTFORD, Conn. — Families of two of the 20 first-graders killed in the Sandy Hook Elementary School shooting are suing the town of Newtown and its board of education, alleging security measures at the school weren't adequate.

The wrongful death lawsuit served on the town Friday is being filed by the parents of Jesse Lewis and Noah Pozner, who were among the children fatally shot Dec. 14, 2012. The families are seeking unspecified damages in the lawsuit, which is expected to be filed in state Superior Court in Danbury in the coming weeks.

Among the allegations is that Sandy Hook Elementary School had security policies and procedures in place that teachers weren't able to follow on the day of the killings. Classroom doors could only be locked from the outside with keys, leaving teachers vulnerable to intruders, and the front of the school didn't have security glass to protect against gunshots, according to the lawsuit.

The lawsuit alleges a teacher in one of the two classrooms where students were killed was a substitute, didn't have a key and didn't receive training on the security protocols.

"We are hopeful that the town of Newtown's elected and hired representatives will work with these families, who have already suffered, and continue to suffer, unimaginable loss, to help resolve this matter in the most efficient and constructive way possible," Donald Papcsy, a lawyer for Lewis and Pozner's parents, said in a statement.

"As residents of the town, we all either have, or are going to have, students in our Sandy Hook schools, and we promote the idea of learning from the past and protecting our children in the future."

Town Attorney David Grogins said the town was served with the lawsuit Friday. He declined further comment. School board members did not immediately respond to requests for comment Monday.

The gunman, 20-year-old Adam Lanza, shot his way into the front entrance of the school, which was locked at the time, and killed the 20 children and six educators, then shot himself to death, state police said. Before going to the school, he killed his mother in their Newtown home, state police said.

Last month, the families of nine of the slain victims filed a lawsuit in state court against the maker and sellers of the Bushmaster AR-15 rifle that Lanza used in the shooting, saying the gun should not have been sold for civilian use because of its overwhelming firepower.

Reports by state police and the state child advocate said Lanza's parents, educators and others missed signs of how deeply troubled he was and opportunities to steer him toward more appropriate treatment for his mental health problems.

Lanza's obsessions with firearms, death and mass shootings have been documented by police files, and investigators previously concluded the motive for the shootings may never be known.