Search continues for chemical weapons in Lincolnshire
A Lincolnshire wood remains closed a week after canisters containing mustard gas were unearthed.
Police and other agencies are continuing to search Roughton Moor Woods, near Woodhall Spa, Lincolnshire. Sonar is being used to help search a nearby lake.
Two people were treated in hospital for minor burns after making the find.
A woman and two men have been arrested and bailed on suspicion of possessing a noxious substance.
Lincolnshire Police said investigators were "conducting tests and removing the contaminated items".
Ch Insp Dan Whyment said he appreciated the public's patience and said the search would continue this week "and possibly beyond".
"We're very much aware that people want to see the woodland reopened and we're doing our best to make sure that this happens as soon as possible," he said.
"We hope that people aren't unduly worried as we've been working at the location for some time now.
"I'd like to reiterate that this is simply to ensure that we are being thorough and public safety remains our priority."
Officers have also searched addresses in Woodhall Spa and Lincoln, but no further noxious substances were recovered.
The canisters found at Roughton Moor are believed to be leftover from an RAF station and military base which was on the site from 1942 until it closed in the late 1960s.
Mustard gas was used as a weapon during World War One and outlawed by the Geneva Protocol of 1925.
The people burnt when they unearthed canisters had been digging for vintage bottles in the woods.