Three sets of old human remains have been found inside Londonderry's historic walls.
The remains were unearthed at an archaeological dig at Bishop Street car park, near St Augustine's cemetery on Friday.
The remains may have been there since the 17th Century, according to researchers.
Archaeologist Emily Murray said: "Below bulks of mud, I came across skulls."
She added: "You can actually see the seams in the cranium.
"The big question is who the people are and how they died.
"It has taken a week and we are now down into two or three layers of garden-type soil. The finds in this layer seem to be 17th Century. We also found a 17th Century coin.
"The Siege of Derry certainly comes to mind but we don't know if these remains are related as of yet."
Researchers at the site said that the depth of soil is not an indication of age.
Derry came under siege between 1688 and 1689.
Dr Eamon Ó Chiardha, from the Department of History in The University of Ulster, said: "An excavation like this can tell us a lot about key events in the 17th Century.
"All we can do is speculate at this stage but it's extremely exciting.
"There were more people inside the walls in 1690 than there were outside besieging them.
"Sieges are usually associated with mass burials."