Eyewitnesses are reporting that children at Spalding Parish Church of England School were locked in the premises while an armed man waved a shotgun nearby this afternoon.
Roads in the Clay lake area were closed off near the school as armed police from Spalding and other areas dealt with the man.
They have now been reopened following the incident and police, who remain in the area,have denied social media rumours that someone was shot.
Some roads were closed around 5pm, causing traffic jams as people returned home from work, but all were reopened by 7.30pm.
A police statement released during the incident read: “We are asking people to be patient while we have some temporary road closures in place.”
And Spalding Chief Inspector Jim Tyner tweeted: “I am seeing rumours on Twitter. Incident in Clay Lake has ended peacefully. No shots fired and no one harmed.”
He added that roads were only closed for the safety of the public and that detours could not always be quickly arranged as officers from away are sometimes used in what could be major incidents.