NORWALK — Doris Glenn clutched her cellphone while standing across County Street from Norwalk High School on Tuesday morning, anxiously awaiting updates on the shelter-in-place situation inside.

She was one of the first parents who rushed to the school after police arrived in force on a report of a person who might have had a weapon. Police vehicles were parked all around the building, and 15 to 20 officers — some with military-style rifles — came to the scene to investigate. Outer doors of the building were secured, and no one was allowed to come inside or leave.

Glenn had already been anxious about sending her son back to school in the wake of the high school massacre in Parkland, Florida, where 17 students and educators were slain six days earlier.

“This morning, when I bring my son to school, I tell him, ‘William, listen — if you see someone with a gun or a knife just move it and go and you know what you have to do. Go tell the principal. Or if they start shooting, lie over there or something like that,” she said.

Such scenes have played out more than two dozen times at schools around the nation in days since the attack at Marjory Stoneman Douglas High School in Florida, with possible threats being made against schools or fears of weapons on campuses.

Norwalk High was put on “shelter in place” mode shortly after 10:45 a.m., and though a district statement said everyone was safe and that is was “business as usual” inside, it was anything but that for the anxious parents outside, at least one of them in tears. Relatives posted questions and expressed dismay on social media.

The action began at 10:43 a.m. after school staff told a school resource officer that a student “believed they had heard someone pulling the slide back on a handgun in a men’s room within the school at 8:30 a.m.,” police spokesman Lt. Terry Blake said. “At no time did the student see a firearm and at no time were there any threats made.”

Blake said police conducted an investigation for several hours while students were “sheltered in place.” He said no weapon was seen or found, and that no students were detained or arrested. No arrests were expected, he said Tuesday evening.

“In the climate we live in today, with what has obviously just happened in Parkland, Florida, we take everything — no matter how innocuous — very seriously,” Blake said. “There's protocols in place and these protocols were exercised today.”

While school administrators tried to continue with classes, many students were distracted and texting with worried parents.

Ethan Carpio was in the orchestra room with other students.

“It was supposed to be class was normal, but since the tension was high because of the recent event, no one was really continuing class as normally," he said. “We just kind of sat there for a couple of hours and every once in a while we’d get an announcement. We didn’t get any information, really.”

Administrators dismissed students at 1:30 p.m. Students were weren’t allowed to retreive backpacks or jackets.

However, many of parents who waited for answers outside the school said they were frustrated with what they felt was lack of communication. There was also a language barrier for a large portion of parents who spoke only Spanish, as more than one-third of the students are Hispanic. Parents also received different accounts of what happened from their children, adding to the confusion.

Diana Carpio was one of the dozens of parents who rushed to Norwalk High after receiving text from her son. Others came after they received a text from the district’s messaging system around 11:30 a.m. about the school being under a “shelter” alert.

“He definitely told me it was a drill and then he texted me and told me that it was not a drill,” Carpio said, referring to her conversation with her son. She called the school before the alert was sent out, and said she was told it was a drill.

Norwalk Public Schools spokeswoman Brenda Wilcox-Williams was not aware of such a mixup, said the call might have happened before facts were confirmed.

“In situations like this, the circumstances evolve pretty rapidly and we get official communications out as soon as we possibly can,” Wilcox-Williams said. “And we always try to direct people to the official district sources as well.”

The district’s messenger system sends out news through text, email, Facebook, Twitter and automated phone calls, such as the one parents received at 1:30 p.m. to alert them about the early dismissal.

“We use those to get information as soon as we confirmed the facts especially when there is an urgent situation,” Wilcox-Williams said. “In 2018, (parents) are going to get a text from their children but these students may not always have the correct information.”

Norwalk High School Principal Reginald Roberts reiterated that point, saying in a statement Tuesday that “rumors and misinformation on other sources can make things much more difficult.”

He commended staff and students for executing set safety procedures the district has in place. And as a follow-up, grade-level assemblies will be held Wednesday to answer any questions students have, to remind them to use the Anonymous Alerts system and to review safety protocols with regards to lockdowns and shelter-in-place protocols.

“With the news last week out of Parkland, Florida, we know these are challenging times," Roberts said. “Please know that when an emergency might be underway, our first priority is making sure that students and staff are safe.”

The district also bolstered security for this week, as other school districts across the nation have done in the wake of the school shooting in Florida.

Norwalk Public Schools Safety Coordinator Joe Rios sent out a district-wide memo Monday saying there would be a more visible police presence at city schools this week to ensure the safety of returning students. Norwalk students had been out of schools since Thursday.

He also noted several security upgrades this year, including the installation of digital cameras and new surveillance equipment in strategic areas throughout the schools and monitors will soon be installed at the police department as well. Staff have been trained in using them and are also trained to use of a software application that tracks visitors in and out of the schools.

Secondary students and parents also now have access to the Anonymous Alerts app introduced in the fall.; 203-842-2568; @stephaniehnkim