They are asking for answers after the Richmond School was put in lockdown following an incident involving a 'disruptive' pupil.
Police attended the incident just after noon on Monday but said they left without taking action and the incident "was resolved quickly".
Parents received a text at 12.01pm informing them the school was in "full lockdown situation" .
The message said: "All the children are safe. During this period the telephones and entrances will be unmanned , external doors and windows unlocked and no personnel allowed in our out."
Parents immediately headed for the school and one told the Skegness Standard: "Richmond Drive was full within 15 minutss of the first message.
"Everyone was worried sick. The headteacher came out and said their had been an incident but she couldn’t comment at the time but that it was all under control."
A second text was sent at 12.47pm when the lockdown had ended and explaining that a child had been in "a high state of anxiety". The text said: "The children are all well and happy, we practice lockdown once or twice a year and they all believe this was one of these premises."
Many parents took to social media when the Skegness Standard published a report on the incident online.
Parent Chris Woods said: "I think the way some parents behaved is ridiculous.
"The message clearly stated that the office would be unattended, so why so many parents came down and kicked off is baffling.
"If they had just waited for updates then it wouldn't of got out of hand like it did."
It was claimed a parent contacted the police and a school governor, Stephanie Preston-Hall, said: "I understand that parents were worried but the staff are highly trained in these situations. The school didn’t call the police or need them."
Parent Kylie Wilkinson commented: "They (the parents) were probably worried sick about their child/children and wanted answers."
Kylie told our newspaper she was not happy about the way the incident was handled and would be speaking to the headteacher. She said: "It wasn’t necessary to call the police but it was necessary for children to sit under a table for over an hour, in the dark and in silence?.
"If the child was that disruptive the teachers should have contained that child in the hall where it first started. Yes, lock the classroom door to stop the child entering and causing more mayhem, but the rest of it was unnecessary.
"The children all came out of school subdued and quiet. One girl was apparently sick when she was under the table from fright and lots of children were crying."
Joanne Hazard, of the Richmond School in Richmond Drive, said: "The safety of our pupils is our top priority, and we have clear policies in place to deal with significant incidents.
"We experienced an incident with a pupil who was being disruptive, so, as a precaution, the school was briefly locked down, ensuring children and staff could then continue learning without distraction.
"The situation was quickly resolved and the matter will be addressed appropriately.
"We followed our procedures and policies and swiftly informed our school community whilst we resolved the situation."
Lincolnshire Police said: "Officers attended the school around 12.30pm today following a report the school had been locked down.
"Our officers did not take any action and left shortly after."