EMERGENCY services cordoned off a Dorset road after workmen unearthed a dangerous cache of home-made World War II grenades.
A 50-metre cordon was put in place in the centre of Swanage while emergency services waited for the arrival of bomb disposal experts.
The grenades were discovered at around 3pm today as excavation work was being done at Shore Road.
They were thought to be releasing phosphine gas.
Dorset Fire and Rescue’s district commander for Purbeck, Mike Cox, said workmen had been carrying out ground-levelling when they uncovered a quantity of number 76 special incendiary grenades.
The grenades consist of bottles containing phosphorus, which is exposed to the air when the bottles are smashed.
The Home Guard kept caches of them during World War II in case of a German invasion.
Two of the grenades were smashed as workmen uncovered them. Four were found but the bomb disposal team is expected to look for more.
Richard Coleman from Dorset Fire and Rescue Service said: “There are excavation works taking place in the area.
"What seems likely is that they are old phosphorous grenades from the war.
“When the bottles get broken phosphorous comes into contact with the air.
“It’s a fairly common occurrence. A cordon is in place and we are keeping people away from the area.”
Dorset Police are advising members of the public to stay away from the area.
A spokesperson from the force said: "At 3pm today, Monday 12 May 2014, Dorset Police received a report of possible dangerous materials.
"Chemical bottles had been uncovered and disturbed on a building site on Shore Road, Swanage.
“Officers are working with Dorset Fire and Rescue Service and EOD [Explosive Ordnance Disposal].
“A cordon has been put in place for safety reasons.
“Police are requesting that the public stays away from the area so the material can be dealt with.”
Paramedics were called to the scene to check over workers at the site as a precaution.
A spokesperson from South Western Ambulance service said three people who were exposed to the gas were treated at the scene.