Dozens of mustard gas canisters were cleared from two websites in Lincolnshire, police have mentioned.
Officers mentioned 140 were recovered from Roughton Moor Woods, whilst 10 had been discovered in Stixwould Lake.
A significant decontamination operation is beneath approach after gas canisters had been first unearthed on 1 October, in which two other folks suffered minor burns.
Three other folks arrested on suspicion of possessing a noxious substance were bailed.
Royal Navy and Army bomb disposal groups were operating with the emergency products and services the use of drones and sonar apparatus at the search close to Woodhall Spa.
Sonar pictures appearing a crate of mustard gas canisters on the backside of Stixwould Lake were launched, whilst water samples from the lake were taken away for lab assessments.
East Lindsey District Council mentioned the world round Woodhall Spa can be fenced off whilst decontamination takes position.
A public assembly organised via the council used to be held at Petwood Hotel on Thursday to replace citizens.
Supt Phil Vickers, of Lincolnshire Police, advised the assembly 22 other companies were concerned in the operation.
A lady and two males had been arrested after the preliminary in finding previous this month.
The canisters discovered at Roughton Moor are believed to be from an RAF station and army base which used to be at the website online from 1942 till it closed in the past due 1960s.
Mustard gas used to be used as a weapon right through World War One and outlawed via the Geneva Protocol of 1925.
The other folks burnt once they unearthed canisters were digging for antique bottles in the woods.