Police are looking for witnesses after finding a trail of blood smeared across signs, lamp posts, bins, and gates which appeared overnight across Brough and Elloughton.
The trail of blood led police through several streets including Hunter Road, Welton Low Road, Elloughton Road and Springfield Avenue.
The blood stains were reported as happening on Sunday night through to Monday morning, and there were several police vehicles in Elloughton early on Monday afternoon as they appeared to locate a man who may have been connected with the incidents.
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At around 2.30pm on Monday, officers surrounded an elderly man, dressed in a blue tracksuit, who had a heavily-bandaged hand, after finding him sat at a bus stop outside a children's nursery on Elloughton Road.
Witnesses said he appeared "intoxicated" and police were talking calmly to him.
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Earlier that day, witnesses had said police were searching several streets and social media pages were flooded with messages about the mystery.
It concerned and also baffled residents, who posted on a community page: "Omg this is really disturbing. I hope the police get to the bottom of it and it can get cleaned up. Hope whose ever the blood belongs too is OK."
Another resident commented: "I noticed what looked to me like blood on Welton Low Rd this morning walking the dog. Concerned me too."
Another reported: "There's a single male sat at the bus stop just past the park on the left towards the lights. Badly cut left hand, police holding up traffic to deal with him as I drove by about 20 mins ago.
"There were also two police women coming out the garden on the corner of Hunter Road and Elloughton road with an evidence bag."
Humberside Police later issued a statement appealing for witnesses to come forward.
"Officers investigating the circumstances surrounding blood found on several lampposts on Elloughton Road, Brough yesterday evening (Sunday, June 13) are appealing for witnesses to come forward," a spokesperson said.
"It is thought that an unknown individual may have sustained an injury on Elloughton Road before walking in the direction of Main Street.
"At this stage, there are not thought to have been any crimes committed, however we are concerned for the welfare of this individual, who may require medical attention.
"We are asking for anyone who witnessed anything, or anyone who may have information about the incident to contact us by calling our non-emergency number 101 quoting log 284 of June 13."