Near Dalnegorsk, a mining town in Primorsky Krai in the Soviet Far East, local residents reportedly observed a strange reddish-orange sphere approximately one meter in diameter moving across the sky. 

The object appeared to be traveling at a relatively low altitude. According to witnesses, it moved toward Izvestkovaya Hill, commonly known as Height 611, before apparently crashing into or colliding with the mountainside. 

What made the case particularly intriguing was what investigators reportedly discovered afterward. Around the apparent impact site, they found unusual traces, including small glassy or melted patches on rocks, metallic-looking particles, blackened material, tiny spheres, and unusual metallic droplets with an unexplained chemical composition. Some of the material was reportedly so hard that it could only be cut using a diamond saw blade. 

Unlike many UFO cases based entirely on eyewitness testimony, the Dalnegorsk incident appeared to offer something potentially testable: physical material. According to accounts of the investigation, these samples were subsequently examined by Soviet scientists.  

The case remains controversial, however, with questions surrounding the origin of the material, the interpretation of the scientific analyses, and claims that information about the incident was later suppressed by Soviet authorities.